Case of the Missing Tickets

Are your detective hats ready? The Case of the Missing Tickets has begun!

Four tickets to The International Exhibit of Sherlock Holmes have gone missing, and it is up to you to solve the mystery!

Throughout the next week, clues will be released on the Science Center's Twitter page, and it will be up to you to decipher the clues and figure out where these tickets can be located. From October 1 to October 7th, clues will be released regularly to point you in the right direction. Once the final clue is released on October 7, you will be able to find and claim the prize. However, you must be quick! Only the first detective to decipher the clues and get to the mystery location will be able to collect the prize after noon on the 7th. The prize? A package of four free general admission tickets to the museum, four free passes to The International Exhibition of Sherlock Holmes, a family membership to the museum and valuable mystery gifts.

The prize will not be available until all 7 clues have been released, so remember to check @SLSC on Twitter so that you can out sleuth the competition. Also, be sure to contribute any theories you may have throughout the week. The Game is afoot!

 

 

Week of Monday, September 29

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, September 29.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, October 3, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:55 a.m. on Monday, September 29 and sunset is at 6:47 p.m. providing us with about 12 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 1.5 hours.  This period of time is called twilight, which ends around 8:15 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 12:51 p.m. this week.

On October 23 the Moon will pass between the Earth and Sun.  This happens once a month during new moon but when they are aligned just right we see the Moon pass in front of the Sun or what is called a solar eclipse.  The October 23 solar eclipse will only be a partial eclipse but it will still be interesting to see.  The eclipse starts for us in St. Louis around 4:41 p.m.  As the Moon gradually moves in front of the Sun you will see a dark disk obscure it.  By 5:47 p.m. which is the greatest extent of the eclipse you will only see about 36% of the Sun covered by the Moon.  If you have a safe means to observe the eclipse you just need to find a high point nearby with a clear view of the west.  If you do not have a safe way to observe the Sun you can tune in to live.slooh.com where they will broadcast the eclipse live.  The eclipse will still be in progress as the sun sets on St. Louis. 

***************************************************************************************************************

Unfortunately solar eclipse can only be safely observed if you have safe solar filters or some kind of projection device.  You should NEVER look directly at the Sun through an unfiltered telescope, binocular, camera or without solar filter glasses. 

Below you will find links that have information about the October 23 partial eclipse, how you can safely observe solar eclipse and why looking at the Sun will cause serious eye damage that could lead to loss of vision.  I would highly recommend reading the eye damage link. 

http://eclipse.gsfc.nasa.gov/OH/OHfigures/OH2014-Fig04.pdf

http://www.mreclipse.com/Totality2/TotalityCh11.html#Pinhole

http://www.mreclipse.com/Special/filters.html       

Moonrise for Monday, September 29 occurs at 12:04 p.m. and moonset will occur at 10:24 p.m.  On Monday, September 29 the Moon will be exhibiting a waxing crescent phase with about 28% of the lunar disk illuminated.  First quarter moon occurs on October 1 at 2:33 p.m.

On Wednesday, October 8 the Moon will pass through the Earth’s shadow treating us to the second total lunar eclipse of 2014.  A lunar eclipse occurs when the Moon passes through the Earth’s shadow.  On October 8 the Moon will begin its slow trek through our shadow at 3:15 a.m.  At 4:14 a.m. it will begin to enter the darkest part of the Earth’s shadow and finally totality will start at 5:25 a.m. and end at 6:24 a.m.

Leading up to totality the Moon will gradually become darker until it is completely within the umbral portion of our shadow.  When this occurs the Moon will usually exhibit a reddish color.  The reason for the color change is that in the umbral portion of Earth’s shadow there is a little light that passes through our atmosphere.  Our atmosphere scatters shorter wavelengths of light but allows for the longer red wavelengths to filter through.  This dim red light is what illuminates the Moon during a total lunar eclipse.  Red is the typical color but coppery shades of yellow can also occur.  The color we see is dependent on how polluted the stratosphere is.  The typical pollutants that affect the Moon’s color are aerosols lofted high into the stratosphere by volcanic eruptions and forest fires. 

You will have to get up early to catch this eclipse but as no two are exactly alike it will be worth losing a few Z’s to catch one of nature’s most beautiful shows.  The same aerosols that affect the Moon’s color during an eclipse can also affect the colors we see during sunrise.  If any ash clouds are over your viewing location sunsets and sunrises can display very vivid purple, pink and orange colors giving the horizon a fiery appearance.  So perhaps while enjoying October’s total lunar eclipse we may also enjoy a beautiful volcanic sunrise.  Below you will find maps and additional information regarding this total lunar eclipse.

http://eclipse.gsfc.nasa.gov/OH/OHfigures/OH2014-Fig03.pdf

http://www.skyandtelescope.com/astronomy-news/observing-news/total-lunar-eclipse-09262014/

International Space Station (ISS) Observing

Visible passes of ISS from St. Louis this week occur during the morning and evening hours.  The best of these are on the mornings of September 30, October 2 and on the evening of October 6.  To learn more about these passes and others follow the links below.

Catch ISS flying over St. Louis in the morning and evening hours starting Monday, September 29. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

30 Sep

-3.0

05:24:40

37

NNW

05:25:46

64

NE

05:29:04

10

ESE

01 Oct

-0.7

04:38:22

21

E

04:38:22

21

E

04:39:44

10

ESE

01 Oct

-1.9

06:11:17

14

W

06:13:10

22

SW

06:15:48

10

S

02 Oct

-2.2

05:25:08

32

S

05:25:08

32

S

05:27:19

10

SSE

04 Oct

-0.9

20:23:48

10

SSW

20:24:35

16

SSW

20:24:35

16

SSW

05 Oct

-1.8

19:35:19

10

S

19:37:51

20

SE

19:38:16

20

ESE

06 Oct

-2.8

20:21:47

10

WSW

20:24:38

59

W

20:24:38

59

W

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Mars

Mars is now in the constellation Libra and rises before the Sun sets.  Mars can be seen with Saturn in the southwestern skies about 20 minutes after sunset.  Mars will continue to pull away from Saturn as it heads into the constellation Scorpius.  Mars will set by 21:40 p.m. 

Jupiter

The largest planet in the solar system is visible once again in the morning skies.  Jupiter can be found rising by 2:45 a.m. and will be easily visible by 3:30 a.m.    

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 20:47 p.m.  Saturn can be found near the bright double star Zubenelgenubi.     

Uranus and Neptune Opposition 2014

The two most distant planets in our solar system will be at their best for the next couple of months.  Neptune has already reached opposition and Uranus will reach opposition on October 7, 2014.  The opposition of a planet is when it is in opposition with the Sun.  What that means is a planet or other body such as an asteroid is seen on the opposite side of the Earth than the Sun is.  From our perspective this is when an object is at its brightest and also coincides with the object’s closest approach to the Earth.  Only objects further from the Sun than we are can be in opposition. 

Of the two planets Uranus will be the brightest.  Uranus is already appearing as a 5.8 magnitude object and will continue to brighten until October 7.  Uranus is normally a planet that requires binoculars to be seen but when the planet is nearing opposition dark sky observers can see it with the unaided eye.  Through telescopes observers will resolve Uranus into a small disk shaped object that may display a slight greenish blue color.  Large telescopes using high magnifications up to 300x might be able to discern dark and light patches called albedo features.  These features require large aperture telescopes and better than average viewing conditions to be seen. 

Uranus is currently in the constellation Pisces.  Pisces is very difficult to see in light polluted skies so it is better to start with the Great Square of Autumn.  This asterism connects the constellations Andromeda and Pegasus all of which will be seen high in the eastern sky by 10:00 p.m.  As the Great Square sits high in the east if you follow a line connecting the stars Scheat (Beta Peg) through Algenib (Gamma Peg) about the same distance that lays between the two stars you will find three stars the stand next to one another in a straight line.  The brightest of these stars is Delta Piscium.  Uranus is about four degrees south of these stars.  You will need either a desktop planetarium program or detailed star chart to help you pinpoint which star like object is Uranus. 

http://www.iau.org/static/public/constellations/gif/PSC.gif

http://www.iau.org/static/public/constellations/gif/PEG.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Neptune reached opposition on August 29, 2014.  It is now at its peak brightness of 7.8 magnitude.  This means that you will need at least binoculars to see this distant planet even when it is at its brightest.  Through binoculars Neptune will appear as a dim star like object in the constellation Aquarius.  To find Neptune first locate the bright star Fomalhaut.  About 6 to 10 degrees north of Fomalhaut you will find six bright stars that are shaped like a hyperboloid.  Scanning the sky further north you will find the star Sigma Aquarii.  Neptune will be just east of this star.      

Using a telescope most will see a star like object that when magnified enough will reveal a greyish blue disk.  Using a large telescope and high magnification up to 300x it may be possible to detect albedo features and Neptune largest moon Triton.  Triton will appear as a dim star right next to Neptune.

Like Uranus Neptune will require some kind of astronomy software of a detailed map to find.  As we pass by these planets in our orbit see if you can detect there shift amongst the background stars.  Below are a few links that will be helpful in locating Neptune and the stars mentioned above.

http://www.iau.org/static/public/constellations/gif/AQR.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

This month we will once again forego a single constellation and discuss a number of different patterns.  This month we will work on finding some of the informal groupings of stars called asterisms.  These informal patterns can be large groups that contain multiple constellations or they can be small dim groupings that require a telescope to see. Many of them serve as useful markers in the sky that help you find dimmer and more difficult objects.  

The first asterism we will cover in October is the Summer Triangle.  This is one we have mentioned and used numerous times in the night sky update.  Last week in fact we used it in reference to finding Cygnus the Swan.  Other constellations that comprise this asterism are Lyra the Harp and Aquila the Eagle.  Inside the Summer Triangle we find the constellations Vulpecula the Fox, Sagitta the Arrow and just outside the eastern edge is Delphinus the Dolphin.  Scattered throughout these constellations are many gems for double star observers, numerous open star clusters and a number of nebulas.  The first step in finding all of these is taken by first locating the Summer Triangle

Also of interest regarding the Summer Triangle is a Mission called Kepler.  This is a space telescope that steadily observed the patch of sky between Cygnus and Lyra.  What Kepler was looking for was the subtle changes in a star’s light due to the effects of a planet orbiting around it.  Thanks to the Kepler mission and other research programs scientists currently have 5,022 candidate exoplanets (planets orbiting other stars) of which 1,746 have been confirmed.  With these numbers scientists have estimated that there are likely as many planets as there are stars in the Milky Way galaxy if not more.  If you would like to learn more about Kepler and the hunt for exoplanets visit http://planetquest.jpl.nasa.gov/  

With a name like the Summer Triangle you would think that we would start losing this asterism soon as we approach winter.  Due to the longer nights we will continue to see the Summer Triangle for the rest of the year.  Tonight go outside and simply look straight up and you should see the three bright stars Deneb, Vega and Altair that define the triangle shape.  Once you can find this asterism grab some binocular and a reclined chair and just start scanning this part of the sky.  Dense star fields and numerous stars clusters will keep you busy for some time. 

Our next Star Party will be held on Friday, October 3, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on October 3, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.
This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

Week of Monday, September 22

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, September 22.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, October 3, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:49 a.m. on Monday, September 22 and sunset is at 7:58 p.m. providing us with about 12 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 1.5 hours.  This period of time is called twilight, which ends around 8:27 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 12:54 p.m. this week.

September 22 marks the first day of fall.  This day is called the fall or autumnal equinox and on this day the Sun will set roughly due west as the northern hemisphere begins to tilt away from the Sun.  We will see the Sun set further and further south until the first day of winter which is called the winter solstice.  The seasons of Earth are not caused by proximity to the Sun but rather how the Earth’s axes are inclined with respect to the Sun.  To learn more about the Earth’s seasons visit http://aa.usno.navy.mil/faq/docs/seasons_orbit.php    

Moonrise for Monday, September 22 occurs at 5:18 a.m. and moonset will occur at 6:05 p.m.  On Monday, September 22 the Moon will be exhibiting a waning crescent phase with about 2% of the lunar disk illuminated.  New Moon occurs on September 24.

International Space Station (ISS) Observing

Visible passes of ISS this week occur during the morning hours.  The best of these are on the mornings of September 27 and 29.  To learn more about these passes and others follow the links below.

Catch ISS flying over St. Louis in the morning hours starting Monday, September 22. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

23 Sep

-0.5

06:16:24

10

N

06:17:53

12

NNE

06:19:22

10

NE

25 Sep

-0.9

06:14:27

10

NNW

06:17:00

20

NNE

06:19:33

10

ENE

26 Sep

-0.5

05:25:47

10

NNW

05:27:47

15

NNE

05:29:47

10

ENE

27 Sep

-2.1

06:12:40

10

NW

06:15:51

41

NNE

06:19:01

10

ESE

28 Sep

-1.3

05:24:25

14

NNW

05:26:37

26

NNE

05:29:29

10

E

29 Sep

-0.6

04:37:43

18

NE

04:37:43

18

NE

04:39:44

10

ENE

29 Sep

-3.3

06:10:58

10

NW

06:14:17

69

SW

06:17:34

10

SE

30 Sep

-2.9

05:24:02

38

NNW

05:25:06

63

NE

05:28:24

10

ESE

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°. 

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Mars

Mars is now in the constellation Libra and rises before the Sun sets.  Mars can be seen with Saturn in the southwestern skies about 20 minutes after sunset.  Mars will continue to pull away from Saturn as it heads into the constellation Scorpius.  Mars will set by 21:50 p.m. 

Jupiter

The largest planet in the solar system is visible once again in the morning skies.  Jupiter can be found rising by 3:07 a.m. and will be easily visible by 3:45 a.m.    

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 21:12 p.m.  Saturn can be found near the bright double star Zubenelgenubi.      

Uranus and Neptune Opposition 2014

The two most distant planets in our solar system will be at their best for the next couple of months.  Neptune has already reached opposition and Uranus will reach opposition on October 7, 2014.  The opposition of a planet is when it is in opposition with the Sun.  What that means is a planet or other body such as an asteroid is seen on the opposite side of the Earth than the Sun is.  From our perspective this is when an object is at its brightest and also coincides with the object’s closest approach to the Earth.  Only objects further from the Sun than we are can be in opposition. 

Of the two planets Uranus will be the brightest.  Uranus is already appearing as a 5.8 magnitude object and will continue to brighten until October 7.  Uranus is normally a planet that requires binoculars to be seen but when the planet is nearing opposition dark sky observers can see it with the unaided eye.  Through telescopes observers will resolve Uranus into a small disk shaped object that may display a slight greenish blue color.  Large telescopes using high magnifications up to 300x might be able to discern dark and light patches called albedo features.  These features require large aperture telescopes and better than average viewing conditions to be seen. 

Uranus is currently in the constellation Pisces.  Pisces is very difficult to see in light polluted skies so it is better to start with the Great Square of Autumn.  This asterism connects the constellations Andromeda and Pegasus all of which will be seen high in the eastern sky by 10:00 p.m.  As the Great Square sits high in the east if you follow a line connecting the stars Scheat (Beta Peg) through Algenib (Gamma Peg) about the same distance that lays between the two stars you will find three stars the stand next to one another in a straight line.  The brightest of these stars is Delta Piscium.  Uranus is about four degrees south of these stars.  You will need either a desktop planetarium program or detailed star chart to help you pinpoint which star like object is Uranus. 

http://www.iau.org/static/public/constellations/gif/PSC.gif

http://www.iau.org/static/public/constellations/gif/PEG.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Neptune reached opposition on August 29, 2014.  It is now at its peak brightness of 7.8 magnitude.  This means that you will need at least binoculars to see this distant planet even when it is at its brightest.  Through binoculars Neptune will appear as a dim star like object in the constellation Aquarius.  To find Neptune first locate the bright star Fomalhaut.  About 6 to 10 degrees north of Fomalhaut you will find six bright stars that are shaped like a hyperboloid.  Scanning the sky further north you will find the star Sigma Aquarii.  Neptune will be just east of this star.      

Using a telescope most will see a star like object that when magnified enough will reveal a greyish blue disk.  Using a large telescope and high magnification up to 300x it may be possible to detect albedo features and Neptune largest moon Triton.  Triton will appear as a dim star right next to Neptune.

Like Uranus Neptune will require some kind of astronomy software of a detailed map to find.  As we pass by these planets in our orbit see if you can detect there shift amongst the background stars.  Below are a few links that will be helpful in locating Neptune and the stars mentioned above.

http://www.iau.org/static/public/constellations/gif/AQR.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

The constellation of the month for September is Cygnus the Swan.  Cygnus is one of the prominent constellations of the Summer Triangle.  It is easily found by locating the bright star Deneb which represents that tail of the Swan.  The head of the swan is the star Albireo and the wings contain the bright stars Epsilon and Zeta Cygni on the east, Gamma Cygni in the middle and Delta and Theta Cygni on the west.

There are a number of stories associated with the constellation Cygnus.  One of the most prominent involves Zeus disguised himself as a swan to seduced the Spartan queen Leda.  From this encounter Leda produced an egg from which the twins of Gemini emerged.  One was Castor the mortal son of King Tyndareus and the other was Pollux the immortal son of Zeus. 

The first object we will cover in Cygnus is the double star Albireo.  This is the fifth brightest star in Cygnus even though it was given the Bayer designation of Beta Cygni.  This star is about 430 light years away and to the unaided eye looks to be just one star.  The singular appearance changes once you point binoculars at Albireo.  Through lower power binoculars you can just see that Albireo separates into two different stars.  Albireo A is the brighter of the two appearing yellow in color.  It is a K-class giant star that is fusing helium at its core.  It is a star that is 950 times brighter, 50 times larger and 5 times more massive than the Sun.  Its companion Albireo B is a hot B-class or blue dwarf star that is 190 times brighter and about 3.3 times more massive than the Sun.  Alberio B is also a star that rotates very rapidly causing it to spin off some of its own material into a disk of gas that surrounds the star.  Periodically this gas is ionized by Alberio B causing its light to change it spectral qualities for a brief time. 

The two stars are separated by about 34 arc minutes making them an easy split in small telescopes and binoculars.  If they are a true binary system the two stars would take about 100,000 years to orbit one another. 

To find Albireo simply follow the bright stars from the tail star Denib down to the head of the swan.  Albireo marks the head of the swan.  Below you find a map that will help you identify Cygnus and its bright stars.     

http://www.iau.org/static/public/constellations/gif/CYG.gif

The object for the week of September 8 is the variable star SS Cygni.  This star is a cataclysmic variable star that suddenly brightens from about 12th magnitude to roughly 8th magnitude every 4 to 10 weeks.  This type of variable star is called a dwarf nova of which the prototype star for the class is U Geminorum.  These are stars that have a long period of quiescence and then abruptly over a few hours will brighten by 2 to 5 magnitudes.  There is some thought that perhaps SS Cygni deserves its own category as it gets much brighter than U Geminorum and could be a different class of variable.  Either way this is a spectacular variable star to watch as it is has a quick and dynamic rise to maxima which it will then hold for about a week or two until it quickly fades back down to minima.  SS Cygni is currently exhibiting an outburst and should stay at maxima for the next week or two.   

What causes the variance in SS Cygni is that it’s not one but two stars.  One is a K5-class dwarf star that has about 0.60 solar masses and the other is an evolved white dwarf star that has about 0.40 solar masses.  The two stars orbit one another at a close distance of about 100,000 miles taking only 6.5 hours to complete one orbit.  Mass from the companion star begins to transfer onto an accretion disk surrounding the white dwarf star.  When enough material collects onto this disk it becomes unstable and collapses onto the white dwarf.  As this occurs the matter in the accretion disk releases its gravitational potential energy which is the release that causes the nova. 

To find SS Cygni you will have to do a fair bit of star hoping.  Ultimately to find SS Cygni you need to locate the red giant star 75 Cyg.  There are various ways to find this star but all of them will test your skills of star hoping and your ability to recognize dim star fields.  What I do is I locate a few different bright stars using any binocular.  I tend to use the stars Deneb, 56 Cyg, 58 Cyg, Sigma Cyg, 74 Cyg, 76 Cyg and 77 Cyg.  These stars form a large 10 degree arc that extends below Deneb to the west about 10 degrees.  The last two are in a close group of three stars that make a nice reference point when looking for 75 Cyg.  Once you can find 75 Cyg, SS Cygni will be a little more than one degree to the north and west of 75 Cyg.  SS Cygni sits on the edge of a small triangle of stars that is made of 8th to 10th magnitude stars.  When SS Cygni has an outburst there will be a fourth star on one of the triangle’s edge. 

With the moon phase being gibbous for the rest of the week it will restrict views of SS Cygni to large binoculars or a telescope.  It is possible that as the Moon continues to wane smaller binoculars could pick up SS Cygni but anything under 50mm will be a stretch.  Below you will find links to a basic star map and other helpful information regarding this variable star.  On the IAU star map included look for Rho Cygni and the next bright star to the west is 75 Cyg.  From here using some kind of planetarium software should get you to SS Cygni.  I would recommend stellarium for this purpose. 

http://www.iau.org/static/public/constellations/gif/CYG.gif

http://www.aavso.org/tmp3/d6422.png

http://www.aavso.org/types-variables

The object for the week of September 15 is the open star cluster M29.  This little open cluster contains approximately 50 stars which lie at a distance of about 4,000 light years.  The stars in this cluster are around10 million years old and are part of the Cygnus OB1 association.  OB Stellar associations are groupings of 10 to a few hundred massive hot O and B class stars.  The stars in these associations tend to have the same or similar ages and are representative of periods of star formation.  Frequently these massive hot stars will excite the molecular clouds that are near them creating beautiful emission nebulae.  Great examples of these are the North American Nebula (NGC 7000), the Lagoon Nebula (M8) and the Great Orion Nebula (M42).  The Cygnus OB1 association which M29 is a part of contributes to the excitation of a large molecular complex called the Cygnus X region.  This is a bright radio source in Cygnus that has been found to be one of the largest star forming regions in the Milky Way.  

Observing M29 with binoculars will reveal a small fuzzy patch of light.  Small telescopes will reveal about 6 bright stars.  These are all blue supergiant stars that individually are around 160,000 times brighter than the Sun.  The six bright stars visible in a small telescope appear to be in the shape of a hyperboloid and are thus frequently called the Cooling Tower cluster. 

To find M29 first locate the constellation Cygnus as describe above.  Then find the bright star Gamma Cygni.  From here scan about 1.5 degrees to the southeast and you will find M29.  Again through binoculars it appears as a small fuzzy patch of light and through telescopes individual stars will be resolved.  Follow the links below for more information about M29 and those objects associated with it. 

http://www.iau.org/static/public/constellations/gif/CYG.gif

http://messier.seds.org/m/m029.html

http://apod.nasa.gov/apod/ap120118.html

The object for the week of September 22 is the object called Cygnus X-1.  Last month we spent a little time in Cygnus when we talked about the Cygnus Star Cloud.  One of the individual objects listed as part of the star cloud was Cygnus X-1.  Since we discussed this interesting object I thought we would revisit it and describe how to find Cygnus X-1. 

For those that are not familiar with Cygnus X-1 it was the first bright x-ray object that was believed to be a black hole.  It was first detected by a sounding rocket that was launched in 1964.  X-rays are blocked by our atmosphere so astronomical x-ray sources went unnoticed until we could send x-ray detectors high enough into the atmosphere.  Since its discovery Cygnus X-1 has been studied extensively and was eventually found to be the first candidate for a stellar class black hole.

A key component to confirming Cygnus X-1 as a black hole was the discovery that Cygnus X-1 was part of a binary system that contains a blue supergiant star called HDE 226868.  The two objects orbit each other 18.6 million miles apart taking only 5.6 days to complete one orbit.  That is about 20% of the distance between the Earth and Sun.  In addition to seeing the bright x-ray object in the stars vicinity they also noted that when observing the spectrum of HDE 226868 that is spectral signature would change.  HDE 226868 is a star that is between 20 to 40 solar masses.  Like most stars of this mass the outer atmosphere of HDE 226868 is extremely turbulent and is likely a progenitor of a Wolf Rayet star.  The mass that HDE 226868 sheds falls onto an accretion disk surrounding Cygnus X-1.  As this material accelerates and heats up it releases the x-rays that are detected from this object.  Additionally the in falling material is accelerated to relativistic speeds allowing it to release some of its gravitational potential energy.  This energy released generates outflowing jets of particles that have relativistic speeds and are perpendicular to the accretion disk.  The presence of these jets is another confirmation that Cygnus X-1 is a black hole.

The binary system is often reference as V1357 Cyg.  This indicates it is a variable system that changes its brightness.  Finding V1357 is pretty simple but it will require large binoculars or a small telescope to see.  The first step in finding V1357 Cyg is to locate Cygnus the Swan.  Once you have done this you then need to locate the star Eta Cygni.  This is a 4th magnitude star that should be visible to the unaided eye unless you live in the heart of a light polluted city.  Once you have found Eta Cygni look about 0.5 degrees to the north and you will find V1357 Cyg. 

The tricky part will be pinpointing which of the dim stars seen here is V1357 Cyg.  I use planetarium software called Stellarium that that allows me to zoom in enough to see 10th to 11th magnitude stars.  At this scale there are two distinct patterns of stars that emerge.  One is a small rhombus shape of stars.  Just below this you will see an upside down U-shape.  V1357 is in the middle of the U-shape of stars next to another star that is a bit brighter than it. 

We won’t actually see the black hole but we can see its companion star.  An interesting experiment would be to image this star with a spectrometer to see if there is a noticeable red and blue shift present in the stars visible spectrum.  As the black hole orbits the blue star it would tug on it potential causing a Doppler effect in the stars spectrum.  It would be interesting to see if the low res spectrometers some amateur astronomers have could pick up this Doppler shift in HDE 226868’s light. 

This week’s and last week’s objects have provided challenging targets that push our ability to star hop.  Many objects that seem out of reach are often quite easy to see once you take your time and learn the dimmer star fields.  I highly recommend that if either of the last two objects has inspired you to go out and try your luck at finding them that you consider joining a local astronomy club.  A benefit of joining many astronomy clubs is that you gain membership to the Astronomical League.  The Astronomical League has a number of observing programs that will keep you busy for many years to come.  Many of these programs are designed to help you push your own abilities and understanding of astronomy.  Below you will find links to maps, Stellarium software and the local St. Louis astronomy clubs.  If you do not live near St. Louis chances are there is something in your area as well.

http://www.iau.org/static/public/constellations/gif/CYG.gif

http://www.aavso.org/tmp3/d7061.png

http://slasonline.org/

http://www.asemonline.org/

http://nightsky.jpl.nasa.gov/clubs-and-events.cfm

http://www.astroleague.org/observing.html

http://stellarium.org/

Our next Star Party will be held on Friday, October 3, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on October 3, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.
This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

Week of Monday, September 15

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, September 15.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, October 3, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:43 a.m. on Monday, September 15 and sunset is at 7:09 p.m. providing us with about 12.5 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 1.5 hours.  This period of time is called twilight, which ends around 8:39 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 12:56 p.m. this week.       

Moonrise for Monday, September 15 occurs at 11:56 p.m. and moonset will occur at 2:28 p.m. on the following day.  On Monday, September 15 the Moon will be exhibiting a last quarter phase with about 50% of the lunar disk illuminated.

International Space Station (ISS) Observing

Visible passes of ISS this week occur during the morning hours.  The best of these are on the mornings of September 16 and 17.  To learn more about these passes and others follow the links below.

Catch ISS flying over St. Louis in the morning hours starting Monday, September 15. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

15 Sep

-2.2

04:43:04

46

ENE

04:43:04

46

ENE

04:45:32

10

NE

15 Sep

-1.3

06:16:54

10

WNW

06:19:15

18

NNW

06:21:37

10

NNE

16 Sep

-1.8

05:29:22

21

WNW

05:30:21

25

NNW

05:33:10

10

NNE

17 Sep

-1.5

04:42:37

27

NNE

04:42:37

27

NNE

04:44:34

10

NE

17 Sep

-0.7

06:17:43

10

NW

06:18:53

11

NNW

06:20:03

10

N

18 Sep

-1.0

05:28:38

13

NW

05:29:42

14

NNW

05:31:36

10

NNE

19 Sep

-0.7

04:41:39

16

N

04:41:39

16

N

04:42:58

10

NNE

21 Sep

-0.3

04:40:17

11

N

04:40:17

11

N

04:40:47

10

N

 

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°. 

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Mars

Mars is now in the constellation Libra and rises before the Sun sets.  Mars can be seen with Saturn in the southwestern skies about 20 minutes after sunset.  Mars will continue to pull away from Saturn as it heads into the constellation Scorpius.  Mars will set by 22:12 p.m. 

Jupiter

The largest planet in the solar system is visible once again in the morning skies.  Jupiter can be found rising by 3:45 a.m. and will be easily visible by 4:15 a.m.    

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 22: p.m.  Saturn can be found near the bright double star Zubenelgenubi.       

Uranus and Neptune Opposition 2014

The two most distant planets in our solar system will be at their best for the next couple of months.  Neptune has already reached opposition and Uranus will reach opposition on October 7, 2014.  The opposition of a planet is when it is in opposition with the Sun.  What that means is a planet or other body such as an asteroid is seen on the opposite side of the Earth than the Sun is.  From our perspective this is when an object is at its brightest and also coincides with the object’s closest approach to the Earth.  Only objects further from the Sun than we are can be in opposition. 

Of the two planets Uranus will be the brightest.  Uranus is already appearing as a 5.8 magnitude object and will continue to brighten until October 7.  Uranus is normally a planet that requires binoculars to be seen but when the planet is nearing opposition dark sky observers can see it with the unaided eye.  Through telescopes observers will resolve Uranus into a small disk shaped object that may display a slight greenish blue color.  Large telescopes using high magnifications up to 300x might be able to discern dark and light patches called albedo features.  These features require large aperture telescopes and better than average viewing conditions to be seen. 

Uranus is currently in the constellation Pisces.  Pisces is very difficult to see in light polluted skies so it is better to start with the Great Square of Autumn.  This asterism connects the constellations Andromeda and Pegasus all of which will be seen high in the eastern sky by 10:00 p.m.  As the Great Square sits high in the east if you follow a line connecting the stars Scheat (Beta Peg) through Algenib (Gamma Peg) about the same distance that lays between the two stars you will find three stars the stand next to one another in a straight line.  The brightest of these stars is Delta Piscium.  Uranus is about four degrees south of these stars.  You will need either a desktop planetarium program or detailed star chart to help you pinpoint which star like object is Uranus. 

http://www.iau.org/static/public/constellations/gif/PSC.gif

http://www.iau.org/static/public/constellations/gif/PEG.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Neptune reached opposition on August 29, 2014.  It is now at its peak brightness of 7.8 magnitude.  This means that you will need at least binoculars to see this distant planet even when it is at its brightest.  Through binoculars Neptune will appear as a dim star like object in the constellation Aquarius.  To find Neptune first locate the bright star Fomalhaut.  About 6 to 10 degrees north of Fomalhaut you will find six bright stars that are shaped like a hyperboloid.  Scanning the sky further north you will find the star Sigma Aquarii.  Neptune will be just east of this star.      

Using a telescope most will see a star like object that when magnified enough will reveal a greyish blue disk.  Using a large telescope and high magnification up to 300x it may be possible to detect albedo features and Neptune largest moon Triton.  Triton will appear as a dim star right next to Neptune.

Like Uranus Neptune will require some kind of astronomy software of a detailed map to find.  As we pass by these planets in our orbit see if you can detect there shift amongst the background stars.  Below are a few links that will be helpful in locating Neptune and the stars mentioned above.

http://www.iau.org/static/public/constellations/gif/AQR.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

The constellation of the month for September is Cygnus the Swan.  Cygnus is one of the prominent constellations of the Summer Triangle.  It is easily found by locating the bright star Deneb which represents that tail of the Swan.  The head of the swan is the star Albireo and the wings contain the bright stars Epsilon and Zeta Cygni on the east, Gamma Cygni in the middle and Delta and Theta Cygni on the west.

There are a number of stories associated with the constellation Cygnus.  One of the most prominent involves Zeus disguised himself as a swan to seduced the Spartan queen Leda.  From this encounter Leda produced an egg from which the twins of Gemini emerged.  One was Castor the mortal son of King Tyndareus and the other was Pollux the immortal son of Zeus. 

The first object we will cover in Cygnus is the double star Albireo.  This is the fifth brightest star in Cygnus even though it was given the Bayer designation of Beta Cygni.  This star is about 430 light years away and to the unaided eye looks to be just one star.  The singular appearance changes once you point binoculars at Albireo.  Through lower power binoculars you can just see that Albireo separates into two different stars.  Albireo A is the brighter of the two appearing yellow in color.  It is a K-class giant star that is fusing helium at its core.  It is a star that is 950 times brighter, 50 times larger and 5 times more massive than the Sun.  Its companion Albireo B is a hot B-class or blue dwarf star that is 190 times brighter and about 3.3 times more massive than the Sun.  Alberio B is also a star that rotates very rapidly causing it to spin off some of its own material into a disk of gas that surrounds the star.  Periodically this gas is ionized by Alberio B causing its light to change it spectral qualities for a brief time. 

The two stars are separated by about 34 arc minutes making them an easy split in small telescopes and binoculars.  If they are a true binary system the two stars would take about 100,000 years to orbit one another. 

To find Albireo simply follow the bright stars from the tail star Denib down to the head of the swan.  Albireo marks the head of the swan.  Below you find a map that will help you identify Cygnus and its bright stars.       

http://www.iau.org/static/public/constellations/gif/CYG.gif

The object for the week of September 8 is the variable star SS Cygni.  This star is a cataclysmic variable star that suddenly brightens from about 12th magnitude to roughly 8th magnitude every 4 to 10 weeks.  This type of variable star is called a dwarf nova of which the prototype star for the class is U Geminorum.  These are stars that have a long period of quiescence and then abruptly over a few hours will brighten by 2 to 5 magnitudes.  There is some thought that perhaps SS Cygni deserves its own category as it gets much brighter than U Geminorum and could be a different class of variable.  Either way this is a spectacular variable star to watch as it is has a quick and dynamic rise to maxima which it will then hold for about a week or two until it quickly fades back down to minima.  SS Cygni is currently exhibiting an outburst and should stay at maxima for the next week or two.   

What causes the variance in SS Cygni is that it’s not one but two stars.  One is a K5-class dwarf star that has about 0.60 solar masses and the other is an evolved white dwarf star that has about 0.40 solar masses.  The two stars orbit one another at a close distance of about 100,000 miles taking only 6.5 hours to complete one orbit.  Mass from the companion star begins to transfer onto an accretion disk surrounding the white dwarf star.  When enough material collects onto this disk it becomes unstable and collapses onto the white dwarf.  As this occurs the matter in the accretion disk releases its gravitational potential energy which is the release that causes the nova. 

To find SS Cygni you will have to do a fair bit of star hoping.  Ultimately to find SS Cygni you need to locate the red giant star 75 Cyg.  There are various ways to find this star but all of them will test your skills of star hoping and your ability to recognize dim star fields.  What I do is I locate a few different bright stars using any binocular.  I tend to use the stars Deneb, 56 Cyg, 58 Cyg, Sigma Cyg, 74 Cyg, 76 Cyg and 77 Cyg.  These stars form a large 10 degree arc that extends below Deneb to the west about 10 degrees.  The last two are in a close group of three stars that make a nice reference point when looking for 75 Cyg.  Once you can find 75 Cyg, SS Cygni will be a little more than one degree to the north and west of 75 Cyg.  SS Cygni sits on the edge of a small triangle of stars that is made of 8th to 10th magnitude stars.  When SS Cygni has an outburst there will be a fourth star on one of the triangle’s edge. 

With the moon phase being gibbous for the rest of the week it will restrict views of SS Cygni to large binoculars or a telescope.  It is possible that as the Moon continues to wane smaller binoculars could pick up SS Cygni but anything under 50mm will be a stretch.  Below you will find links to a basic star map and other helpful information regarding this variable star.  On the IAU star map included look for Rho Cygni and the next bright star to the west is 75 Cyg.  From here using some kind of planetarium software should get you to SS Cygni.  I would recommend stellarium for this purpose. 

http://www.iau.org/static/public/constellations/gif/CYG.gif

http://www.aavso.org/tmp3/d6422.png

http://www.aavso.org/types-variables

The object for the week of September 15 is the open star cluster M29.  This little open cluster contains approximately 50 stars which lie at a distance of about 4,000 light years.  The stars in this cluster are around10 million years old and are part of the Cygnus OB1 association.  OB Stellar associations are groupings of 10 to a few hundred massive hot O and B class stars.  The stars in these associations tend to have the same or similar ages and are representative of periods of star formation.  Frequently these massive hot stars will excite the molecular clouds that are near them creating beautiful emission nebulae.  Great examples of these are the North American Nebula (NGC 7000), the Lagoon Nebula (M8) and the Great Orion Nebula (M42).  The Cygnus OB1 association which M29 is a part of contributes to the excitation of a large molecular complex called the Cygnus X region.  This is a bright radio source in Cygnus that has been found to be one of the largest star forming regions in the Milky Way.  

Observing M29 with binoculars will reveal a small fuzzy patch of light.  Small telescopes will reveal about 6 bright stars.  These are all blue supergiant stars that individually are around 160,000 times brighter than the Sun.  The six bright stars visible in a small telescope appear to be in the shape of a hyperboloid and are thus frequently called the Cooling Tower cluster. 

To find M29 first locate the constellation Cygnus as describe above.  Then find the bright star Gamma Cygni.  From here scan about 1.5 degrees to the southeast and you will find M29.  Again through binoculars it appears as a small fuzzy patch of light and through telescopes individual stars will be resolved.  Follow the links below for more information about M29 and those objects associated with it. 

http://www.iau.org/static/public/constellations/gif/CYG.gif

http://messier.seds.org/m/m029.html

http://apod.nasa.gov/apod/ap120118.html                                     

Our next Star Party will be held on Friday, October 3, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on October 3, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.
This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

Week of Monday, September 8

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, September 8.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, October 3, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:36 a.m. on Monday, September 8 and sunset is at 7:20 p.m. providing us with less than 13 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 1.5 hours.  This period of time is called twilight, which ends around 8:51 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 12:59 p.m. this week.      

Moonrise for Monday, September 8 occurs at 7:01 p.m. and moonset will occur at 7:15 a.m. on the following day.  On Monday, September 8 the Moon will be full.  September’s full moon is known as the Full Harvest Moon.

September’s full moon is also a perigee syzygy moon.  This means that full moon coincides with when the moon is at its closest to the Earth in its orbit or what is called perigee.  The term syzygy is used when three celestial bodies are in a line with one another which occurs every full moon (Moon-Earth-Sun).  Put the two together and you have a perigee syzygy moon or what some have called a supermoon.  During these events the Moon appears a bit brighter and a bit larger but other than that nothing out of the ordinary occurs.  Keep in mind that the three bodies don’t have to be in a straight line just fall along the same line of sight.  If the Moon, Earth and Sun are in a straight line this is when you see either a solar or lunar eclipse.  In October we will enjoy both a total lunar eclipse (October 8) and a partial solar eclipse (October 23).  We will talk more about these as we get into October.   

International Space Station (ISS) Observing

Visible passes of ISS this week occur during the morning hours.  The best of these are on the mornings of September 12, 14 and 15.  To learn more about these passes and others follow the links below.

Catch ISS flying over St. Louis in the morning hours starting Monday, September 8. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

10 Sep

-0.5

05:31:02

10

SSE

05:33:01

15

SE

05:35:01

10

E

12 Sep

-2.4

05:29:43

17

SSW

05:31:57

45

SE

05:35:09

10

ENE

13 Sep

-1.4

04:43:18

24

SE

04:43:18

24

SE

04:46:02

10

ENE

14 Sep

-3.1

05:29:40

31

WSW

05:31:00

58

NW

05:34:17

10

NE

15 Sep

-2.2

04:43:02

45

ENE

04:43:02

45

ENE

04:45:29

10

NE

15 Sep

-1.3

06:16:51

10

WNW

06:19:12

18

NNW

06:21:33

10

NNE

 

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Mars

Mars is now in the constellation Libra and rises before the Sun sets.  Mars can be seen with Saturn in the southwestern skies about 20 minutes after sunset.  Mars will continue to pull away from Saturn as it heads into the constellation Scorpius.  Mars will set by 22:14 p.m. 

Jupiter

The largest planet in the solar system is visible once again in the morning skies.  Jupiter can be found rising by 3:48 a.m. and will be easily visible by 4:20 a.m.    

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 22:30 p.m.  Saturn can be found near the bright double star Zubenelgenubi.   

Those with a telescope and maybe even those with binoculars will have a chance to watch one of Saturn’s moons Rhea occult a bright 7.6 magnitude star called SAO 159034.  An occultation is a celestial event that occurs when one body is hidden from view by another body that passes in front of the occulted body.  These are typically caused by the Moon, asteroids and planets. 

On September 12 around 8:38 p.m. CDT you can watch as the bright star SAO 159034 will significantly dim for about 30 seconds as Saturn’s moon Rhea (10.2 mag) passes in front of the star.  Events like this can often provide insight to the shape, size and behavior of the occulting body or can provide information about a star such as if it is a multiple star system. 

Much like eclipses, an occultation is only visible to a small part of the Earth.  This is one of the best occultations visible from North America this year.  The challenge will be in find a viewing location that provides you with a clear view of the southwestern horizon.  Below you will find a link to a Sky and Telescope article that gives further information regarding this celestial event.

http://www.skyandtelescope.com/astronomy-news/observing-news/see-saturns-moon-rhea-hide-star-09032014/ 

Uranus and Neptune Opposition 2014

The two most distant planets in our solar system will be at their best for the next couple of months.  Neptune has already reached opposition and Uranus will reach opposition on October 7, 2014.  The opposition of a planet is when it is in opposition with the Sun.  What that means is a planet or other body such as an asteroid is seen on the opposite side of the Earth than the Sun is.  From our perspective this is when an object is at its brightest and also coincides with the object’s closest approach to the Earth.  Only objects further from the Sun than we are can be in opposition. 

Of the two planets Uranus will be the brightest.  Uranus is already appearing as a 5.8 magnitude object and will continue to brighten until October 7.  Uranus is normally a planet that requires binoculars to be seen but when the planet is nearing opposition dark sky observers can see it with the unaided eye.  Through telescopes observers will resolve Uranus into a small disk shaped object that may display a slight greenish blue color.  Large telescopes using high magnifications up to 300x might be able to discern dark and light patches called albedo features.  These features require large aperture telescopes and better than average viewing conditions to be seen. 

Uranus is currently in the constellation Pisces.  Pisces is very difficult to see in light polluted skies so it is better to start with the Great Square of Autumn.  This asterism connects the constellations Andromeda and Pegasus all of which will be seen high in the eastern sky by 10:00 p.m.  As the Great Square sits high in the east if you follow a line connecting the stars Scheat (Beta Peg) through Algenib (Gamma Peg) about the same distance that lays between the two stars you will find three stars the stand next to one another in a straight line.  The brightest of these stars is Delta Piscium.  Uranus is about four degrees south of these stars.  You will need either a desktop planetarium program or detailed star chart to help you pinpoint which star like object is Uranus. 

http://www.iau.org/static/public/constellations/gif/PSC.gif

http://www.iau.org/static/public/constellations/gif/PEG.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Neptune reached opposition on August 29, 2014.  It is now at its peak brightness of 7.8 magnitude.  This means that you will need at least binoculars to see this distant planet even when it is at its brightest.  Through binoculars Neptune will appear as a dim star like object in the constellation Aquarius.  To find Neptune first locate the bright star Fomalhaut.  About 6 to 10 degrees north of Fomalhaut you will find six bright stars that are shaped like a hyperboloid.  Scanning the sky further north you will find the star Sigma Aquarii.  Neptune will be just east of this star.      

Using a telescope most will see a star like object that when magnified enough will reveal a greyish blue disk.  Using a large telescope and high magnification up to 300x it may be possible to detect albedo features and Neptune largest moon Triton.  Triton will appear as a dim star right next to Neptune.

Like Uranus Neptune will require some kind of astronomy software of a detailed map to find.  As we pass by these planets in our orbit see if you can detect there shift amongst the background stars.  Below are a few links that will be helpful in locating Neptune and the stars mentioned above.

http://www.iau.org/static/public/constellations/gif/AQR.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Comet Jacques (C/2014 E2)

There is another binocular comet that has been cruising through the early morning skies for most of the summer.  It is now in the constellation Cygnus making it visible all night long.  Comet Jacques (C/2014 E2) was discovered earlier this year in March by the SONEAR observatory team.  It is a long period comet that is estimated to take roughly 22,000 years to orbit the Sun.  It is now on its way back out of the inner solar system and will continue to fade as it gets further from the Sun. 

Currently the bright moonlight is making it difficult to see Comet Jacques (C/2014 E2).  It is expected that the comet will begin to make significant drops in magnitude over this month.  The moonlight will continue to be a problem over the next week so observations of this comet will be difficult.  For those with a telescope or those that want to continue trying to find Comet Jacques (C/2014 E2) with binoculars, it will continue to move down the body of Cygnus for the rest of the week.  My last observations of the comet had it around 7.5 magnitude and it required 15x70 binoculars to be seen.

Below are a number of links to maps and other information that will be helpful.  If you have any questions regarding this comet feel free to send an email to spacequestions@slsc.org.

http://www.skyandtelescope.com/astronomy-news/observing-news/happy-times-comet-watchers-08202014/

http://www.aerith.net/comet/weekly/current.html

http://heavens-above.com/comet.aspx?cid=C%2F2014%20E2&lat=38.627&lng=-90.1994&loc=St.+Louis&alt=141&tz=CST

http://www.iau.org/static/public/constellations/gif/CYG.gif

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

The constellation of the month for September is Cygnus the Swan.  Cygnus is one of the prominent constellations of the Summer Triangle.  It is easily found by locating the bright star Deneb which represents that tail of the Swan.  The head of the swan is the star Albireo and the wings contain the bright stars Epsilon and Zeta Cygni on the east, Gamma Cygni in the middle and Delta and Theta Cygni on the west.

There are a number of stories associated with the constellation Cygnus.  One of the most prominent involves Zeus disguised himself as a swan to seduced the Spartan queen Leda.  From this encounter Leda produced an egg from which the twins of Gemini emerged.  One was Castor the mortal son of King Tyndareus and the other was Pollux the immortal son of Zeus. 

The first object we will cover in Cygnus is the double star Albireo.  This is the fifth brightest star in Cygnus even though it was given the Bayer designation of Beta Cygni.  This star is about 430 light years away and to the unaided eye looks to be just one star.  The singular appearance changes once you point binoculars at Albireo.  Through lower power binoculars you can just see that Albireo separates into two different stars.  Albireo A is the brighter of the two appearing yellow in color.  It is a K-class giant star that is fusing helium at its core.  It is a star that is 950 times brighter, 50 times larger and 5 times more massive than the Sun.  Its companion Albireo B is a hot B-class or blue dwarf star that is 190 times brighter and about 3.3 times more massive than the Sun.  Alberio B is also a star that rotates very rapidly causing it to spin off some of its own material into a disk of gas that surrounds the star.  Periodically this gas is ionized by Alberio B causing its light to change it spectral qualities for a brief time. 

The two stars are separated by about 34 arc minutes making them an easy split in small telescopes and binoculars.  If they are a true binary system the two stars would take about 100,000 years to orbit one another. 

To find Albireo simply follow the bright stars from the tail star Denib down to the head of the swan.  Albireo marks the head of the swan.  Below you find a map that will help you identify Cygnus and its bright stars.       

http://www.iau.org/static/public/constellations/gif/CYG.gif

The object for the week of September 8 is the variable star SS Cygni.  This star is a cataclysmic variable star that suddenly brightens from about 12th magnitude to roughly 8th magnitude every 4 to 10 weeks.  This type of variable star is called a dwarf nova of which the prototype star for the class is U Geminorum.  These are stars that have a long period of quiescence and then abruptly over a few hours will brighten by 2 to 5 magnitudes.  There is some thought that perhaps SS Cygni deserves its own category as it gets much brighter than U Geminorum and could be a different class of variable.  Either way this is a spectacular variable star to watch as it is has a quick and dynamic rise to maxima which it will then hold for about a week or two until it quickly fades back down to minima.  SS Cygni is currently exhibiting an outburst and should stay at maxima for the next week or two.    

What causes the variance in SS Cygni is that it’s not one but two stars.  One is a K5-class dwarf star that has about 0.60 solar masses and the other is an evolved white dwarf star that has about 0.40 solar masses.  The two stars orbit one another at a close distance of about 100,000 miles taking only 6.5 hours to complete one orbit.  Mass from the companion star begins to transfer onto an accretion disk surrounding the white dwarf star.  When enough material collects onto this disk it becomes unstable and collapses onto the white dwarf.  As this occurs the matter in the accretion disk releases its gravitational potential energy which is the release that causes the nova. 

To find SS Cygni you will have to do a fair bit of star hoping.  Ultimately to find SS Cygni you need to locate the red giant star 75 Cyg.  There are various ways to find this star but all of them will test your skills of star hoping and your ability to recognize dim star fields.  What I do is I locate a few different bright stars using any binocular.  I tend to use the stars Deneb, 56 Cyg, 58 Cyg, Sigma Cyg, 74 Cyg, 76 Cyg and 77 Cyg.  These stars form a large 10 degree arc that extends below Deneb to the west about 10 degrees.  The last two are in a close group of three stars that make a nice reference point when looking for 75 Cyg.  Once you can find 75 Cyg, SS Cygni will be a little more than one degree to the north and west of 75 Cyg.  SS Cygni sits on the edge of a small triangle of stars that is made of 8th to 10th magnitude stars.  When SS Cygni has an outburst there will be a fourth star on one of the triangle’s edge. 

With the moon phase being gibbous for the rest of the week it will restrict views of SS Cygni to large binoculars or a telescope.  It is possible that as the Moon continues to wane smaller binoculars could pick up SS Cygni but anything under 50mm will be a stretch.  Below you will find links to a basic star map and other helpful information regarding this variable star.  On the IAU star map included look for Rho Cygni and the next bright star to the west is 75 Cyg.  From here using some kind of planetarium software should get you to SS Cygni.  I would recommend stellarium for this purpose. 

http://www.iau.org/static/public/constellations/gif/CYG.gif

http://www.aavso.org/tmp3/d6422.png

http://www.aavso.org/types-variables                                    

Our next Star Party will be held on Friday, October 3, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on October 3, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.
This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

Week of Monday, September 1

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, September 1.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, September 5, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:30 a.m. on Monday, September 1 and sunset is at 7:31 p.m. providing us with about 13 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 1.5 hours.  This period of time is called twilight, which ends around 9:04 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 1:01 p.m. this week.   

Moonrise for Monday, September 1 occurs at 1:11 a.m. and moonset will occur at 11:37 p.m.  First quarter moon occurs on September 2, 2014 at 6:11 a.m.    

International Space Station (ISS) Observing

There are no visible passes of ISS this week.  ISS will return to our skies on September 10 when it will be seen in the morning hours.  In lieu of ISS sightings below you will find a few excellent Tiangong 1 passes. 

Catch Tiangong 1 flying over St. Louis in evening hours starting Monday, September 1. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

02 Sep

 1.8

20:25:38

10

W

20:28:38

49

NNW

20:31:10

13

ENE

06 Sep

 1.6

20:58:01

10

WNW

21:01:00

47

NNE

21:01:06

47

NNE

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Venus

Venus is now well within its current morning apparition. It rises around 5:20 a.m. becoming visible after 5:50 a.m.  Be aware that the Sun rises about 40 minutes after Venus.  If you are going to try to spot the bright planet make sure to be aware of sunrise times for each day.  Venus is currently exhibiting a gibbous phase with roughly 95% of the Venusian disk illuminated.

Mars

Mars is now in the constellation Libra and rises before the Sun sets.  Mars can be seen with Saturn in the southwestern skies about 20 minutes after sunset.  Mars will continue to pull away from Saturn as it heads into the constellation Scorpius.  Mars will set by 22:27 p.m. 

Jupiter

The largest planet in the solar system is starting to join us once again in the morning skies.  Jupiter can be found rising by 4:08 a.m. becoming visible by 4:40 a.m.  Look for Jupiter and Venus together in the morning skies.  If you watch the two planets over the rest of the month you will notice Jupiter is moving higher in the sky each day while Venus is getting lower in the east each day.  This wandering of the planets is what made ancient astronomers name the planets Aster Planetes or wandering stars.  

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 22:30 p.m.  Saturn can be found near the bright double star Zubenelgenubi.    

Uranus and Neptune Opposition 2014

The two most distant planets in our solar system will be at their best for the next couple of months.  Neptune has already reached opposition and Uranus will reach opposition on October 7, 2014.  The opposition of a planet is when it is in opposition with the Sun.  What that means is a planet or other body such as an asteroid is seen on the opposite side of the Earth than the Sun is.  From our perspective this is when an object is at its brightest and also coincides with the object’s closest approach to the Earth.  Only objects further from the Sun than we are can be in opposition. 

Of the two planets Uranus will be the brightest.  Uranus is already appearing as a 5.8 magnitude object and will continue to brighten until October 7.  Uranus is normally a planet that requires binoculars to be seen but when the planet is nearing opposition dark sky observers can see it with the unaided eye.  Through telescopes observers will resolve Uranus into a small disk shaped object that may display a slight greenish blue color.  Large telescopes using high magnifications up to 300x might be able to discern dark and light patches called albedo features.  These features require large aperture telescopes and better than average viewing conditions to be seen. 

Uranus is currently in the constellation Pisces.  Pisces is very difficult to see in light polluted skies so it is better to start with the Great Square of Autumn.  This asterism connects the constellations Andromeda and Pegasus all of which will be seen high in the eastern sky by 10:00 p.m.  As the Great Square sits high in the east if you follow a line connecting the stars Scheat (Beta Peg) through Algenib (Gamma Peg) about the same distance that lays between the two stars you will find three stars the stand next to one another in a straight line.  The brightest of these stars is Delta Piscium.  Uranus is about four degrees south of these stars.  You will need either a desktop planetarium program or detailed star chart to help you pinpoint which star like object is Uranus. 

http://www.iau.org/static/public/constellations/gif/PSC.gif

http://www.iau.org/static/public/constellations/gif/PEG.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Neptune reached opposition on August 29, 2014.  It is now at its peak brightness of 7.8 magnitude.  This means that you will need at least binoculars to see this distant planet even when it is at its brightest.  Through binoculars Neptune will appear as a dim star like object in the constellation Aquarius.  To find Neptune first locate the bright star Fomalhaut.  About 6 to 10 degrees north of Fomalhaut you will find six bright stars that are shaped like a hyperboloid.  Scanning the sky further north you will find the star Sigma Aquarii.  Neptune will be just east of this star.      

Using a telescope most will see a star like object that when magnified enough will reveal a greyish blue disk.  Using a large telescope and high magnification up to 300x it may be possible to detect albedo features and Neptune largest moon Triton.  Triton will appear as a dim star right next to Neptune.

Like Uranus Neptune will require some kind of astronomy software of a detailed map to find.  As we pass by these planets in our orbit see if you can detect there shift amongst the background stars.  Below are a few links that will be helpful in locating Neptune and the stars mentioned above.

http://www.iau.org/static/public/constellations/gif/AQR.gif

http://www.skyandtelescope.com/astronomy-news/observing-news/uranus-and-neptune-in-2014/

Comet Jacques (C/2014 E2)

There is another binocular comet that has been cruising through the early morning skies for most of the summer.  It is now in the constellation Cygnus making it visible all night long.  Comet Jacques (C/2014 E2) was discovered earlier this year in March by the SONEAR observatory team.  It is a long period comet that is estimated to take roughly 22,000 years to orbit the Sun.  It is now on its way back out of the inner solar system and will continue to fade as it gets further from the Sun. 

To find Comet Jacques (C/2014 E2) first look for the Summer Triangle.  The bright star in the northeast corner of the triangle is called Deneb.  Deneb represents the tail of the constellation Cygnus the Swan.  Once you have identified Deneb and Cygnus look north of Deneb and you will find an elongated house shape of stars.  This is the circumpolar constellation Cepheus.  Comet Jacques (C/2014 E2) will start the week out on the southern edge of Cepheus and will then move into Cygnus for the next two weeks. 

From roughly September 3 to September 6, Comet Jacques will be passing near the bright star Deneb.  These will be ideal dates to try to find this fading comet.  During September Comet Jacques (C/2014 E2) should start to fade in magnitude.  Comets are fickle things and do not always behave as predicted so it could hold on near 7th magnitude mark for some time.  Unfortunately this comet is now headed away from the Sun so it is only a matter of time until it starts to fade.   

The last time I was able to observe this comet it was around 7.5 magnitude. Sadly the last week has been extremely humid and as such has limited our chances of observing Comet Jacques (C/2014 E2).  The most recent night I was able to observe the comet I had to use 15x70 binoculars.  I could no longer see the comet in 10x50 binoculars however the seeing was bad and high level clouds were rolling in.    

Below are a number of links to maps and other information that will be helpful.  If you have any questions regarding this comet feel free to send an email to spacequestions@slsc.org.

http://www.skyandtelescope.com/astronomy-news/observing-news/happy-times-comet-watchers-08202014/

http://www.aerith.net/comet/catalog/2014E2/2014E2.html

http://www.heavens-above.com/comet.aspx?cid=C%2F2014%20E2&lat=38.627&lng=-90.1994&loc=St.+Louis&alt=141&tz=CST

http://www.iau.org/static/public/constellations/gif/CEP.gif

http://www.iau.org/static/public/constellations/gif/CYG.gif

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

The constellation of the month for September is Cygnus the Swan.  Cygnus is one of the prominent constellations of the Summer Triangle.  It is easily found by locating the bright star Deneb which represents that tail of the Swan.  The head of the swan is the star Albireo and the wings contain the bright stars Epsilon and Zeta Cygni on the east, Gamma Cygni in the middle and Delta and Theta Cygni on the west.

There are a number of stories associated with the constellation Cygnus.  One of the most prominent involves Zeus disguised himself as a swan to seduced the Spartan queen Leda.  From this encounter Leda produced an egg from which the twins of Gemini emerged.  One was Castor the mortal son of King Tyndareus and the other was Pollux the immortal son of Zeus. 

The first object we will cover in Cygnus is the double star Albireo.  This is the fifth brightest star in Cygnus even though it was given the Bayer designation of Beta Cygni.  This star is about 430 light years away and to the unaided eye looks to be just one star.  The singular appearance changes once you point binoculars at Albireo.  Through lower power binoculars you can just see that Albireo separates into two different stars.  Albireo A is the brighter of the two appearing yellow in color.  It is a K-class giant star that is fusing helium at its core.  It is a star that is 950 times brighter, 50 times larger and 5 times more massive than the Sun.  Its companion Albireo B is a hot B-class or blue dwarf star that is 190 times brighter and about 3.3 times more massive than the Sun.  Alberio B is also a star that rotates very rapidly causing it to spin off some of its own material into a disk of gas that surrounds the star.  Periodically this gas is ionized by Alberio B causing its light to change it spectral qualities for a brief time. 

The two stars are separated by about 34 arc minutes making them an easy split in small telescopes and binoculars.  If they are a true binary system the two stars would take about 100,000 years to orbit one another. 

To find Albireo simply follow the bright stars from the tail star Denib down to the head of the swan.  Albireo marks the head of the swan.  Below you find a map that will help you identify Cygnus and its bright stars.     

http://www.iau.org/static/public/constellations/gif/CYG.gif                                 

Our next Star Party will be held on Friday, September 5, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on September 5, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.
This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

Week of Monday, August 25

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, August 25.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, September 5, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:24 a.m. on Monday, August 25 and sunset is at 7:41 p.m. providing us with about 13.5 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 1.5 hours.  This period of time is called twilight, which ends around 9:16 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 1:03 p.m. this week.     

Moonrise for Monday, August 25 occurs at 6:29 a.m. and moonset will occur at 7:33 p.m.  New moon occurs on August 25, 2014 at 9:13 a.m.    

International Space Station (ISS) Observing

This week visible passes of ISS are all evening passes.  The two ISS passes this week will be the last for the next two weeks.  After this dry spell we will start seeing ISS again in the early morning hours starting September 10.  To learn more about these passes follow the links in the table.

Catch ISS flying over St. Louis in evening hours starting Monday, August 25. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

25 Aug

-2.3

20:06:36

10

WNW

20:09:48

44

SW

20:12:59

10

SSE

27 Aug

-0.5

20:07:02

10

W

20:08:59

15

SW

20:10:56

10

SSW

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Venus

Venus is now well within its current morning apparition. It rises around 5:05 a.m. becoming visible after 5:30 a.m.  Venus is currently exhibiting a gibbous phase with roughly 95% of the Venusian disk illuminated.

Mars

Mars is now in the constellation Libra and rises before the Sun sets.  Mars can be seen with Saturn in the southwestern skies about 20 minutes after sunset.  By the end of this week Mars will have overpassed Saturn as it wanders eastward into the constellation Scorpius.  Mars will set by 22:41 p.m. 

Jupiter

The largest planet in the solar system is starting to join us once again in the morning skies.  Jupiter can be found rising by 4:29 a.m. becoming visible by 5:00 a.m.  Look for Jupiter and Venus together in the morning skies.  If you watch the two planets over the rest of the month you will notice Jupiter is moving higher in the sky each day while Venus is getting lower in the east each day.  This wandering of the planets is what made ancient astronomers name the planets Aster Planetes or wandering stars.  

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 22:56 p.m.  Saturn can be found near the bright double star Zubenelgenubi.    

Comet Jacques (C/2014 E2)

There is another binocular comet that has been cruising through the early morning skies for most of the summer.  It is now in the constellation Cassiopeia making it visible not long after midnight.  Comet Jacques (C/2014 E2) was discovered earlier this year in March by the SONEAR observatory team.  It is a long period comet that is estimated to take roughly 22,000 years to orbit the Sun.  It is now on its way back out of the inner solar system and will continue to fade as it gets further from the Sun. 

To find Comet Jacques (C/2014 E2) first look for the constellation Cassiopeia.  She will be seen as a bright W-shape of stars rising in the northeast.  Comet Jacques (C/2014 E2) starts the week off in the northern part of Cassiopeia and passes into Cepheus by the end of the week. On August 30 Comet Jacques (C/2014 E2) will pass by the massive and extremely luminous red supergiant star Mu Cephei.  This is one of the largest and most distant stars visible to the unaided eye.  While you look at the comet take some time and enjoy the garnet red color of this dying star giant star.  In the next few million years it is likely to end in extremely energetic explosion called a type II supernova. .

The last time I was able to observe this comet it was still around 7th magnitude. Sadly the last week has been extremely humid and as such has limited our chances of observing Comet Jacques (C/2014 E2).  The few nights I was able to observe the comet I used 8x42 and 10x50 binoculars.  It goes to show that you don’t need to go buy a giant telescope to see some of the amazing objects the sky has to offer. 

Below are a number of links to maps and other information that will be helpful.  If you have any questions regarding this comet feel free to send an email to spacequestions@slsc.org.

http://www.skyandtelescope.com/astronomy-news/observing-news/happy-times-comet-watchers-08202014/

http://www.aerith.net/comet/weekly/current.html

http://heavens-above.com/comet.aspx?cid=C%2F2014%20E2&lat=38.627&lng=-90.1994&loc=St.+Louis&alt=141&tz=CST

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

For August we are going to do things a little different again. This month we will visit three constellations that contain an object called a star cloud.  These are virtually dust free windows into the larger structures of the Milky Way.  This type of object is typically missed by those of us that observe from light polluted locations like St. Louis as the dim glow of the Milky Way’s concentration is washed from view.  The constellations we will visit to find these are Sagittarius, Scutum and Cygnus. 

Star clouds are fascinating structures.  Again they are virtually dust free windows into the larger structures of the Milky Way.  A good analogy for this is to imagine an overcast day.  As you scan the cloudy sky you come across a hole in the clouds giving you an unobscured view of the blue sky.  Just like atmospheric clouds obscure the sky behind them, clouds of dust and gas in our galaxy will obscure the stars that are positioned behind them.  Scattered along the dim glow of the Milky Way are relatively dust free zones that offer bright unobscured views of the dense and distant star fields of the Milky Way’s spiral arms.  Even though a great deal of what star clouds offer is lost to observers with light polluted skies they still offer large vistas of denser star fields and often contain some of the most striking deep sky objects to look for.

When observing these large features in the sky it is best to star with binoculars.  They offer a much wider field of view and can take in more of the dense star field.  Once you have done this for a while then try pointing a telescope into the star clouds. This will yield views of more specific objects such as open star clusters, double/multiple stars and various nebulas. 

The first star cloud we will look at is the Great Sagittarius Star Cloud (GSSC).  As the name implies this star cloud is located in the constellation Sagittarius.  This famous constellation can be found in our southern skies during the summer months.  Due to its low altitude Sagittarius may be hard for some to see if you have tall buildings or trees south of your viewing location.  Finding Sagittarius is pretty simple.  First locate a large fishhook shape of stars in the south.  This is the constellation Scorpius.  Just east of the fishhook you will find another bright group of stars in shape of a stovetop teapot.  This is called the teapot asterism which is the bright part of the constellation Sagittarius. 

Once you have found the Teapot asterism grab some binoculars and scan the patch of sky near the spout of the teapot.  Here is where you will find the Great Sagittarius Star Cloud.  For those of us in light polluted skies this part of the sky will have a noticeably denser star field.  The part of the Milky Way we are looking at here is the Sagittarius arm of the galaxy that sits between us and the center of our galaxy.  Many of the stars you will be able to see in binoculars lie at distances between 6,500 and 13,000 lights years away.  Even in light polluted skies there are thousands of stars scattered in this relatively small patch of sky. 

Getting out to dark skies is where you will see why these structures are called star clouds.  With just the unaided eye the dense fields of these relatively dust free windows into the depths of the Milky Way will be much brighter than the rest of the dust obscured parts of our galaxy’s concentration.  The glow you see here is representative of millions of stars that lie closer to the Milky Way’s core than we do. 

Once you have scanned and taken in the entire star cloud there are a number of other objects that stand out in the same area.  M7 or Ptolemy’s cluster is an open cluster that is much closer to us than the GSSC is.  It will be easily seen as a bright group of roughly 80 stars on the southern boundary of the star cloud.  At only 800 light years away this group of stars is in the same arm (Orion Spur) of the galaxy that the Sun is.  On the north edge of the GSSC is a bright emission nebula called M8 or the Lagoon Nebula.  This is an area where stars are actively forming that lies at about 5,200 light years away.  This stellar nursery is part of the Sagittarius arm of our galaxy and can be easily spotted with small binoculars.  In fact if you scan north of M8 you will find three more nebulae that are also in the Sagittarius arm.  These are named M20, M17 and M16. 

In addition to these nebulae there are a number of open star clusters scatter around the GSSC that can be seen but many will go unnoticed if you just quickly scan through the sky.  Most of the cluster will be around 8th or 9th magnitude and contain fewer than 100 stars. 

To get as much out of the GSSC you will need to spend some quality time soaking in the light for these distant stars.  I would recommend starting with binoculars no larger than 10 x 50.  There will be numerous double stars to identify and a hand full of deep sky objects as well.  Having a desktop planetarium software handy will help you identify some of these but a more detailed database will be required for fainter less obvious objects.  Below you will find basic maps of Sagittarius and Scorpius that will aid you in finding the GSSC and the brighter deep sky objects listed above. 

http://www.iau.org/static/public/constellations/gif/SGR.gif

http://www.iau.org/static/public/constellations/gif/SCO.gif

The star cloud for August 11 is called the Small Sagittarius Star Cloud (SSSC).  Even though the name implies it is lesser in nature this is the densest and my favorite of the star clouds we will look at this month.  The SSSC is also known as M24 as it was one of the objects Charles Messier included in his famous catalog.  Messier described it as a patch of nebulous light with numerous intertwined stars of different magnitudes. 

The SSSC spans about 1.5 degrees of the sky and provides us with a view of stars that fills a volume of the galaxy extending about 16,000 light years deep.  Like last week’s star cloud the SSSC provides us with an unobscured view into the depths of the Sagittarius arm of the Milky Way.

In light polluted skies where the dim glow of the Milky Way cannot be seen the SSSC looks like a collection of bright stars that are organized into long chains and arches.  All together I think they look like an umbrella that has been turned out by strong winds.  It is a very nice view that contains a number of bright stars many of which are double stars. 

Getting out to a dark site where the dim glow of the Milky Way is visible the SSSC will appear as a detached and brighter portion of the Milky Way.  The SSSC is best viewed through binoculars or small telescopes with wide fields of view.  Larger instruments will typically limit your field of view only allowing you to see small portions of the star cloud.  On a clear night using a good solid tripod it is easy to get lost in the myriad of stars in this dense part of the Milky Way.  Once you have spent some time scanning the star cloud there are a number of smaller deep sky objects to look for in the same part of the sky.  The most obvious will be an open star cluster called NGC 6603.  This 11th magnitude cluster will be a fine target in larger binoculars and small telescopes.  In addition to NGC 6603 you may notice two large dark patches in the SSSC.  These are dark nebulae known as B92 and B93.  These are large clumps of dust that block out the light from background stars.  Beyond these more obvious objects there are a number of less obvious clusters, a number of double stars and a planetary nebula to look for using moderate sized telescopes.  For an object that only spans 1.5 degrees of the sky it is densely packed with loads of goodies that will keep you occupied for a long time. 

To find the SSSC look for the teapot shape of Sagittarius described last week.  Using binoculars scan north of the teapot’s top and you will easily identify the compact dense star field of the SSSC.  Below you will find links to a map that will help you locate this object and additional information about the SSSC.  The linked IAU map for Sagittarius does not label the SSSC (M24) but it is located near a star called Mu Sagitarii.  This star will be marked on the map.

http://www.iau.org/static/public/constellations/gif/SGR.gif

http://messier.seds.org/m/m024.html

The star cloud for the week of August 18 is the Scutum Star Cloud (SSC).  Like those covered in the previous weeks the SSC is a relatively dust free window into a deeper portion of the Milky Way.  This window again allows us to peer deeper into the arm of the Milky Way known as the Sagittarius arm. 

To find this part of the Milky Way first locate the three bright stars in the Summer Triangle; Vega, Denib and Altair.  The southern most of the three stars is Altair which is the brightest star in the constellation Aquila the Eagle.  The brightest stars of Aquila take the shape of an elongated diamond with the north/south axis short and the east/west axis long.  If you use binoculars and follow the north/south axis of Aquila’s diamond shape to the south for roughly 10 degrees of sky you will find the star Lambda Aquilae.  Scanning the sky around this star you will see a bright hook shape of stars which demarcates the northern edge of the SSC. 

For observers contending with light pollution that obscures the dim glow of the Milky Way, this hook shape of stars will be the first indicator you are looking at the SSC however most of the bright stars you see in the hook shape are only a few hundred light years away from us.  This means they belong to the same part of the Milky Way the Sun does.  As you scan the sky below the hook shape of stars you will start to notice fainter stars around 7th, 8th and 9th magnitudes.  Many of these fainter stars are giant stars that lie up to 4,000 light years away.  Some of these giant stars are on the nearer edge of our neighboring Sagittarius arm of the galaxy. 

While scanning for these fainter giant stars you will likely notice one or maybe two dim patches of light.  One of them appears near the curve of the hook shape and the other is another five degrees south of the hook shape near the star Delta Scutii.  These dim patches are galactic star clusters known as M11 and M26.  M11 is also known as the Wild Duck Cluster and lies at a distance of about 6,000 light years.  This is a collection of roughly 2,900 stars that are about 220 million years old.  M26 is a little fainter and the member stars are a little more scattered which will make it a tougher cluster to find.  M26 lies about 5,000 light years away and its member stars are a bit over 80 million years old.  Both of these clusters are located in the Sagittarius arm.

Also in the area of the sky covered by the SSC is the classic carbon star V Aquilae.  Carbon stars are usually highly evolved red giant stars that have more carbon than oxygen in their atmospheres.  This allows for carbon compounds to form which are good at scattering light.  The wavelengths that are not affected by this scattering are the red wavelengths so carbon stars appear to be the reddest stars in the sky.  V Aquilae can be found between the stars Lambda and 12 Aquilae.  These are two of the brighter stars in the hook shape.

Getting out to a dark sky site the SSC will appear as one of the brightest parts of the Milky Way.  Scanning this dim glow you will notice several dark patches where clouds of dust obscure parts of the star cloud.  These types of dark dust clouds are called dark nebulae which were cataloged by astronomer Edward Emerson, Barnard.  Barnard’s catalog contains 366 of these dark nebulae many of which can be seen with binoculars on nights with good viewing conditions.  You can find 19 of Barnard’s dark nebulae scattered around the SSC. 

I will include a number constellation maps that are near the SSC to aid in its discovery.  The key will be to find the Summer Triangle and from there it is pretty simple.  Besides the object listed above there is a globular star cluster a planetary nebula and a number of interesting stars in the same vicinity of the SSC.  I would highly recommend using desktop planetarium software such as Stellarium to help you explore this rich part of the sky.

http://www.iau.org/static/public/constellations/gif/SCT.gif

http://www.iau.org/static/public/constellations/gif/AQL.gif

http://www.iau.org/static/public/constellations/gif/CYG.gif

http://www.iau.org/static/public/constellations/gif/LYR.gif

The final star cloud we will cover this month is the Cygnus Star Cloud (CSC).  As the name implies the CSC is located in the constellation Cygnus the Swan.  As is such this will be an easy find for most as Cygnus is one of the prominent constellations of the Summer Triangle.  Simple go out and look straight up for a large triangle shape of bright stars.  By midnight it will be straight over head.  The bright star Denib marks the tail of the swan and its head is marked by the double star Alberio.  The CSC spans about 20 degrees of the sky between the stars Beta Cygnii (Alberio) and Gamma Cygnii (Sadr). 

In light polluted skies if you scan the patch of sky between the two aforementioned stars you will see a noticeably denser star field.  When you are looking into this dust free window you are looking down the arm of the galaxy called the Orion Spur.  This is the part of the Milky Way the Sun belongs to.  Many of the stars you can see here are thousands of light years away from us.

When observing the CSC you can think of it in two halves.  The south half near Alberio has some nice chains of stars but it is pretty sparse when it comes to open star clusters.  The one star cluster that can be observed in this part of the CSC is NGC 6834.  This open cluster contains about 50 stars that are well detached from the background stars.  The northern half of the CSC has a number of open clusters and a large diffuse emission nebula called the crescent nebula.  The shining gem of these objects is an open cluster named M29 or the “Cooling Tower” star cluster.  This is a group of about 50 stars that lies at a distance of about 4,000 light years away.

One of the most intriguing objects in Cygnus is called Cygnus X-1.  Cygnus X-1 is an X-ray source that lies about 6,100 light years away.  It was discovered in 1964 by using suborbital rockets equipped with Geiger counters.  Eventually enough information was discovered about this bright X-ray source that scientists now believe that it is a black hole.  We cannot detect X-rays with our human eyes but we can observe Cygnus X-1’s companion.  Where the X-ray source is found scientists have determined that it forms a spectroscopic binary with a bright blue supergiant star.  This star’s name is V1357 Cyg.  It is 9th magnitude star which means 60mm binoculars will be able to show you this star.  If you have an interest in finding V1357 Cyg you will need a map with stars down to 10th magnitude or a desktop planetarium program such as Stellarium.  V1357 Cyg is near the bright star Eta Cygnii.

For observer in dark locations you will see the CSC as a large bright patch of the Milky Way between the tail and head of the swan.  In last week’s star cloud we talked about dark nebulae.  Near the CSC we can see one of the largest dark features of the Milky Way known as the Cygnus rift or the Great Rift.  This is a series of dark nebulae that start in Cygnus and extends down to Sagittarius creating what looks like a dark lane splitting the Milky Way length wise.  These dark clouds are large masses of molecular material that are associated with large star forming regions in our arm of the Milky Way.  It is a very striking feature that is plainly visible to the unaided eye provided you are in a dark location.  Below you will find a map for Cygnus that will aid you in locating the CSC.  It will not be marked on the map however just remember the stars Beta and Gamma Cygnii lie on either end of the star cloud.  

http://www.iau.org/static/public/constellations/gif/CYG.gif                           

Our next Star Party will be held on Friday, September 5, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on September 5, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.
This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

Week of Monday, August 18.

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, August 18.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, September 5, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:18 a.m. on Monday, August 18 and sunset is at 7:51 p.m. providing us with about 14 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 1.5 hours.  This period of time is called twilight, which ends around 9:29 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 1:05 p.m. this week. 

Moonrise for Monday, August 18 occurs at 12:26 a.m.  Moonset will occur at 2:54 p.m. on the following day.  On Monday, August 18 the Moon will be exhibiting a waning crescent phase with roughly 38% of the lunar disk illuminated.  New moon occurs on August 25, 2014. 

International Space Station (ISS) Observing

This week visible passes of ISS are evening passes.  The best of these occur on the evenings 19, 22 and 23of August.  To learn more about these passes and others this week use the information below.

Catch ISS flying over St. Louis in evening hours starting Monday, August 18. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

18 Aug

-1.1

20:56:41

10

NNW

20:59:07

19

NNE

21:01:08

12

ENE

18 Aug

-0.6

22:32:50

10

NW

22:34:01

20

WNW

22:34:01

20

WNW

19 Aug

-2.9

21:44:23

10

NW

21:47:21

58

N

21:47:21

58

N

20 Aug

-2.3

20:56:01

10

NW

20:59:10

37

NNE

21:00:43

23

E

20 Aug

-0.2

22:33:06

10

W

22:33:36

13

W

22:33:36

13

W

21 Aug

-1.7

20:07:44

10

NNW

20:10:33

25

NNE

20:13:22

10

E

21 Aug

-2.2

21:44:14

10

WNW

21:47:02

38

WSW

21:47:02

38

WSW

22 Aug

-3.3

20:55:36

10

NW

20:58:56

76

SW

21:00:31

28

SE

23 Aug

-3.0

20:07:07

10

NW

20:10:25

59

NE

20:13:42

10

ESE

23 Aug

-0.7

21:45:06

10

W

21:46:47

13

SW

21:46:58

13

SW

24 Aug

-1.3

20:55:41

10

WNW

20:58:26

24

SW

21:00:36

13

S

25 Aug

-2.3

20:06:48

10

WNW

20:10:00

43

SW

20:13:10

10

SSE

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Venus

Venus is now well within its current morning apparition. It rises around 4:49 a.m. becoming visible after 5:15 a.m.  Venus is currently exhibiting a gibbous phase with roughly 95% of the Venusian disk illuminated.

Mars

Mars is now in the constellation Libra and rises before the Sun sets.  For those awake around 9:00 p.m. you will see a reddish-orange object high in the southwest.  We have now passed by Mars in our orbit and will continue to move further away each day.  Mars will set by 22:57 p.m. 

Jupiter

The largest planet in the solar system is starting to join us once again in the morning skies.  Jupiter can be found rising by 4:49 a.m. becoming visible by 5:15 a.m.  Look for Jupiter and Venus together in the morning skies.  If you watch the two planets over the rest of the month you will notice Jupiter is moving higher in the sky each day while Venus is getting lower in the east each day.  This wandering of the planets is what made ancient astronomers name the planets Aster Planetes or wandering stars.  

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 23:23 p.m.  Saturn can be found near the bright double star Zubenelgenubi.    

Keep an eye on Mars and Saturn as the two are approaching each other in the sky.  Later this year Mars will pass Saturn on its way into the constellation Scorpius. 

Comet Jacques (C/2014 E2)

There is another binocular comet that has been cruising through the early morning skies for most of the summer.  It is now near the constellation Perseus making it visible not long after midnight.  Comet Jacques (C/2014 E2) was discovered earlier this year in March by the SONEAR observatory team.  It is a long period comet that is estimated to take roughly 22,000 years to orbit the Sun.  It is now on its way back out of the inner solar system and will continue to fade as it gets further from the Sun. 

To find Comet Jacques (C/2014 E2) first look for the constellation Cassiopeia.  She will be seen as a bright W-shape of stars rising in the northeast.  The western half of the W-shape will point you down to the constellation Perseus.  About halfway down Perseus you will see a bright and broad group of stars called the Alpha Perseii Moving Group.  This star cluster is dominated by a bright star at its center called Mirfak or Alpha Perseii.  Comet Jacques (C/2014 E2) will be passing by this star cluster as it skirts the boundary between Perseus and Camelopardalis.  By the end of the week Comet Jacques (C2014 E2) will be in Cassiopeia. 

The last time I was able to observe this comet it was nearing 7th magnitude on a night when there was considerable light pollution from the Moon.  Even with a gibbous moon drowning out much of the sky I was still able to spot Comet Jacques (C/2014 E2) through a number of different binoculars.  It was easy to see with 10x50 and 8x42 binoculars, it was a bit tougher in 7x35 binoculars and through cheapo 10x25 binoculars I thought I was just barely able to detect the faint glow of the comet.  It goes to show that you don’t need to go buy a giant telescope to see some of the amazing objects the sky has to offer. 

Below are a number of links to maps and other information that will be helpful.  If you have any questions regarding this comet feel free to send an email to spacequestions@slsc.org.

http://freestarcharts.com/images/Articles/Month/Aug2014/Comet_Jacques/C2014_E2_Jacques_Aug14_Finder_Chart.pdf

http://www.aerith.net/comet/catalog/2014E2/2014E2.html

http://heavens-above.com/skychart.aspx?lat=38.627&lng=-90.1994&loc=St.+Louis&alt=141&tz=CST

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

For August we are going to do things a little different again. This month we will visit three constellations that contain an object called a star cloud.  These are virtually dust free windows into the larger structures of the Milky Way.  This type of object is typically missed by those of us that observe from light polluted locations like St. Louis as the dim glow of the Milky Way’s concentration is washed from view.  The constellations we will visit to find these are Sagittarius, Scutum and Cygnus. 

Star clouds are fascinating structures.  Again they are virtually dust free windows into the larger structures of the Milky Way.  A good analogy for this is to imagine an overcast day.  As you scan the cloudy sky you come across a hole in the clouds giving you an unobscured view of the blue sky.  Just like atmospheric clouds obscure the sky behind them, clouds of dust and gas in our galaxy will obscure the stars that are positioned behind them.  Scattered along the dim glow of the Milky Way are relatively dust free zones that offer bright unobscured views of the dense and distant star fields of the Milky Way’s spiral arms.  Even though a great deal of what star clouds offer is lost to observers with light polluted skies they still offer large vistas of denser star fields and often contain some of the most striking deep sky objects to look for.

When observing these large features in the sky it is best to star with binoculars.  They offer a much wider field of view and can take in more of the dense star field.  Once you have done this for a while then try pointing a telescope into the star clouds. This will yield views of more specific objects such as open star clusters, double/multiple stars and various nebulas. 

The first star cloud we will look at is the Great Sagittarius Star Cloud (GSSC).  As the name implies this star cloud is located in the constellation Sagittarius.  This famous constellation can be found in our southern skies during the summer months.  Due to its low altitude Sagittarius may be hard for some to see if you have tall buildings or trees south of your viewing location.  Finding Sagittarius is pretty simple.  First locate a large fishhook shape of stars in the south.  This is the constellation Scorpius.  Just east of the fishhook you will find another bright group of stars in shape of a stovetop teapot.  This is called the teapot asterism which is the bright part of the constellation Sagittarius. 

Once you have found the Teapot asterism grab some binoculars and scan the patch of sky near the spout of the teapot.  Here is where you will find the Great Sagittarius Star Cloud.  For those of us in light polluted skies this part of the sky will have a noticeably denser star field.  The part of the Milky Way we are looking at here is the Sagittarius arm of the galaxy that sits between us and the center of our galaxy.  Many of the stars you will be able to see in binoculars lie at distances between 6,500 and 13,000 lights years away.  Even in light polluted skies there are thousands of stars scattered in this relatively small patch of sky. 

Getting out to dark skies is where you will see why these structures are called star clouds.  With just the unaided eye the dense fields of these relatively dust free windows into the depths of the Milky Way will be much brighter than the rest of the dust obscured parts of our galaxy’s concentration.  The glow you see here is representative of millions of stars that lie closer to the Milky Way’s core than we do. 

Once you have scanned and taken in the entire star cloud there are a number of other objects that stand out in the same area.  M7 or Ptolemy’s cluster is an open cluster that is much closer to us than the GSSC is.  It will be easily seen as a bright group of roughly 80 stars on the southern boundary of the star cloud.  At only 800 light years away this group of stars is in the same arm (Orion Spur) of the galaxy that the Sun is.  On the north edge of the GSSC is a bright emission nebula called M8 or the Lagoon Nebula.  This is an area where stars are actively forming that lies at about 5,200 light years away.  This stellar nursery is part of the Sagittarius arm of our galaxy and can be easily spotted with small binoculars.  In fact if you scan north of M8 you will find three more nebulae that are also in the Sagittarius arm.  These are named M20, M17 and M16. 

In addition to these nebulae there are a number of open star clusters scatter around the GSSC that can be seen but many will go unnoticed if you just quickly scan through the sky.  Most of the cluster will be around 8th or 9th magnitude and contain fewer than 100 stars. 

To get as much out of the GSSC you will need to spend some quality time soaking in the light for these distant stars.  I would recommend starting with binoculars no larger than 10 x 50.  There will be numerous double stars to identify and a hand full of deep sky objects as well.  Having a desktop planetarium software handy will help you identify some of these but a more detailed database will be required for fainter less obvious objects.  Below you will find basic maps of Sagittarius and Scorpius that will aid you in finding the GSSC and the brighter deep sky objects listed above. 

http://www.iau.org/static/public/constellations/gif/SGR.gif

http://www.iau.org/static/public/constellations/gif/SCO.gif

The star cloud for August 11 is called the Small Sagittarius Star Cloud (SSSC).  Even though the name implies it is lesser in nature this is the densest and my favorite of the star clouds we will look at this month.  The SSSC is also known as M24 as it was one of the objects Charles Messier included in his famous catalog.  Messier described it as a patch of nebulous light with numerous intertwined stars of different magnitudes. 

The SSSC spans about 1.5 degrees of the sky and provides us with a view of stars that fills a volume of the galaxy extending about 16,000 light years deep.  Like last week’s star cloud the SSSC provides us with an unobscured view into the depths of the Sagittarius arm of the Milky Way.

In light polluted skies where the dim glow of the Milky Way cannot be seen the SSSC looks like a collection of bright stars that are organized into long chains and arches.  All together I think they look like an umbrella that has been turned out by strong winds.  It is a very nice view that contains a number of bright stars many of which are double stars. 

Getting out to a dark site where the dim glow of the Milky Way is visible the SSSC will appear as a detached and brighter portion of the Milky Way.  The SSSC is best viewed through binoculars or small telescopes with wide fields of view.  Larger instruments will typically limit your field of view only allowing you to see small portions of the star cloud.  On a clear night using a good solid tripod it is easy to get lost in the myriad of stars in this dense part of the Milky Way.  Once you have spent some time scanning the star cloud there are a number of smaller deep sky objects to look for in the same part of the sky.  The most obvious will be an open star cluster called NGC 6603.  This 11th magnitude cluster will be a fine target in larger binoculars and small telescopes.  In addition to NGC 6603 you may notice two large dark patches in the SSSC.  These are dark nebulae known as B92 and B93.  These are large clumps of dust that block out the light from background stars.  Beyond these more obvious objects there are a number of less obvious clusters, a number of double stars and a planetary nebula to look for using moderate sized telescopes.  For an object that only spans 1.5 degrees of the sky it is densely packed with loads of goodies that will keep you occupied for a long time. 

To find the SSSC look for the teapot shape of Sagittarius described last week.  Using binoculars scan north of the teapot’s top and you will easily identify the compact dense star field of the SSSC.  Below you will find links to a map that will help you locate this object and additional information about the SSSC.  The linked IAU map for Sagittarius does not label the SSSC (M24) but it is located near a star called Mu Sagitarii.  This star will be marked on the map.

http://www.iau.org/static/public/constellations/gif/SGR.gif

http://messier.seds.org/m/m024.html

The star cloud for the week of August 18 is the Scutum Star Cloud (SSC).  Like those covered in the previous weeks the SSC is a relatively dust free window into a deeper portion of the Milky Way.  This window again allows us to peer deeper into the arm of the Milky Way known as the Sagittarius arm. 

To find this part of the Milky Way first locate the three bright stars in the Summer Triangle; Vega, Denib and Altair.  The southern most of the three stars is Altair which is the brightest star in the constellation Aquila the Eagle.  The brightest stars of Aquila take the shape of an elongated diamond with the north/south axis short and the east/west axis long.  If you use binoculars and follow the north/south axis of Aquila’s diamond shape to the south for roughly 10 degrees of sky you will find the star Lambda Aquilae.  Scanning the sky around this star you will see a bright hook shape of stars which demarcates the northern edge of the SSC. 

For observers contending with light pollution that obscures the dim glow of the Milky Way, this hook shape of stars will be the first indicator you are looking at the SSC however most of the bright stars you see in the hook shape are only a few hundred light years away from us.  This means they belong to the same part of the Milky Way the Sun does.  As you scan the sky below the hook shape of stars you will start to notice fainter stars around 7th, 8th and 9th magnitudes.  Many of these fainter stars are giant stars that lie up to 4,000 light years away.  Some of these giant stars are on the nearer edge of our neighboring Sagittarius arm of the galaxy. 

While scanning for these fainter giant stars you will likely notice one or maybe two dim patches of light.  One of them appears near the curve of the hook shape and the other is another five degrees south of the hook shape near the star Delta Scutii.  These dim patches are galactic star clusters known as M11 and M26.  M11 is also known as the Wild Duck Cluster and lies at a distance of about 6,000 light years.  This is a collection of roughly 2,900 stars that are about 220 million years old.  M26 is a little fainter and the member stars are a little more scattered which will make it a tougher cluster to find.  M26 lies about 5,000 light years away and its member stars are a bit over 80 million years old.  Both of these clusters are located in the Sagittarius arm.

Also in the area of the sky covered by the SSC is the classic carbon star V Aquilae.  Carbon stars are usually highly evolved red giant stars that have more carbon than oxygen in their atmospheres.  This allows for carbon compounds to form which are good at scattering light.  The wavelengths that are not affected by this scattering are the red wavelengths so carbon stars appear to be the reddest stars in the sky.  V Aquilae can be found between the stars Lambda and 12 Aquilae.  These are two of the brighter stars in the hook shape.

Getting out to a dark sky site the SSC will appear as one of the brightest parts of the Milky Way.  Scanning this dim glow you will notice several dark patches where clouds of dust obscure parts of the star cloud.  These types of dark dust clouds are called dark nebulae which were cataloged by astronomer Edward Emerson, Barnard.  Barnard’s catalog contains 366 of these dark nebulae many of which can be seen with binoculars on nights with good viewing conditions.  You can find 19 of Barnard’s dark nebulae scattered around the SSC. 

I will include a number constellation maps that are near the SSC to aid in its discovery.  The key will be to find the Summer Triangle and from there it is pretty simple.  Besides the object listed above there is a globular star cluster a planetary nebula and a number of interesting stars in the same vicinity of the SSC.  I would highly recommend using desktop planetarium software such as Stellarium to help you explore this rich part of the sky.

http://www.iau.org/static/public/constellations/gif/SCT.gif

http://www.iau.org/static/public/constellations/gif/AQL.gif

http://www.iau.org/static/public/constellations/gif/CYG.gif

http://www.iau.org/static/public/constellations/gif/LYR.gif                     

Our next Star Party will be held on Friday, September 5, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on September 5, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.
This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

Week of Monday, August 11

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, August 11.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, September 5, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 6:11 a.m. on Monday, August 11 and sunset is at 8:00 p.m. providing us with about 14 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 1 and one half hours.  This period of time is called twilight, which ends around 9:40 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 1:06 p.m. this week.     

Moonrise for Monday, August 11 occurs at 8:31 p.m.  Moonset will occur at 8:29 a.m. on the following day.  On Monday, August 11 the Moon will be exhibiting a waning gibbous phase with roughly 98% of the lunar disk illuminated.  Last quarter moon occurs on August 17, 2014. 

International Space Station (ISS) Observing

This week visible passes of ISS are evening passes.  The best of these occur on the evenings of August 16, 17 and 18.  To learn more about these passes and others this week use the information below.

Catch ISS flying over St. Louis in evening hours starting Monday, August 11. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

12 Aug

-0.3

22:35:20

10

N

22:36:45

12

NNE

22:36:50

12

NNE

13 Aug

-0.2

21:47:07

10

N

21:47:26

10

N

21:47:45

10

NNE

14 Aug

-0.6

22:33:19

10

NNW

22:34:53

17

N

22:34:53

17

N

15 Aug

-0.8

21:44:37

10

NNW

21:46:34

15

NNE

21:47:30

13

NE

16 Aug

-0.5

20:56:01

10

N

20:57:14

12

NNE

20:58:27

10

NE

16 Aug

-0.8

22:31:30

10

NW

22:33:00

22

NNW

22:33:00

22

NNW

17 Aug

-1.6

21:42:38

10

NNW

21:45:29

25

NNE

21:45:39

25

NE

18 Aug

-1.1

20:53:51

10

NNW

20:56:13

18

NNE

20:58:21

11

ENE

18 Aug

-0.7

22:29:55

10

NW

22:31:12

22

WNW

22:31:12

22

WNW

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Venus

Venus is now well within its current morning apparition. It rises around 4:35 a.m. becoming visible after 5:00 a.m.  Venus is currently exhibiting a gibbous phase with roughly 94% of the Venusian disk illuminated.

Mars

Mars is now in the constellation Libra and rises before the Sun sets.  For those awake around 9:00 p.m. you will see a reddish-orange object high in the southern skies.  We have now passed by Mars in our orbit and will continue to move further away each day.  Mars will set by 11:13 p.m. 

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 11:50 p.m.  Saturn can be found near the bright double star Zubenelgenubi.    

Keep an eye on Mars and Saturn as the two are approaching each other in the sky.  Later this year Mars will pass Saturn on its way into the constellation Scorpius. 

2014 Perseid Meteor Shower

It is that time of the year again when the Earth sweeps through debris left by comet 109P/ Swfit/Tuttle leading to one of the most spectacular of the meteor showers called the Perseids.  This meteor shower starts at the end of July and lasts up to the end of August.  Peak activity occurs around the 12th and 13th of August with the most meteors visible after midnight.  Sadly this year will not be a good one for the Perseids as we are only two days after full moon.  This will greatly limit the number of meteors visible.  To observe any meteor shower simply go outside and look up.  It is best to look in the direction of the meteor shower’s radiant which is in the northeast for the Perseids.  Below you will find more information regarding the Perseids and other meteor activity. 

http://amsmeteors.org/

http://spaceweather.com/

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

For August we are going to do things a little different again. This month we will visit three constellations that contain an object called a star cloud.  These are virtually dust free windows into the larger structures of the Milky Way.  This type of object is typically missed by those of us that observe from light polluted locations like St. Louis as the dim glow of the Milky Way’s concentration is washed from view.  The constellations we will visit to find these are Sagittarius, Scutum and Cygnus. 

Star clouds are fascinating structures.  Again they are virtually dust free windows into the larger structures of the Milky Way.  A good analogy for this is to imagine an overcast day.  As you scan the cloudy sky you come across a hole in the clouds giving you an unobscured view of the blue sky.  Just like atmospheric clouds obscure the sky behind them, clouds of dust and gas in our galaxy will obscure the stars that are positioned behind them.  Scattered along the dim glow of the Milky Way are relatively dust free zones that offer bright unobscured views of the dense and distant star fields of the Milky Way’s spiral arms.  Even though a great deal of what star clouds offer is lost to observers with light polluted skies they still offer large vistas of denser star fields and often contain some of the most striking deep sky objects to look for.

When observing these large features in the sky it is best to star with binoculars.  They offer a much wider field of view and can take in more of the dense star field.  Once you have done this for a while then try pointing a telescope into the star clouds. This will yield views of more specific objects such as open star clusters, double/multiple stars and various nebulas. 

The first star cloud we will look at is the Great Sagittarius Star Cloud (GSSC).  As the name implies this star cloud is located in the constellation Sagittarius.  This famous constellation can be found in our southern skies during the summer months.  Due to its low altitude Sagittarius may be hard for some to see if you have tall buildings or trees south of your viewing location.  Finding Sagittarius is pretty simple.  First locate a large fishhook shape of stars in the south.  This is the constellation Scorpius.  Just east of the fishhook you will find another bright group of stars in shape of a stovetop teapot.  This is called the teapot asterism which is the bright part of the constellation Sagittarius. 

Once you have found the Teapot asterism grab some binoculars and scan the patch of sky near the spout of the teapot.  Here is where you will find the Great Sagittarius Star Cloud.  For those of us in light polluted skies this part of the sky will have a noticeably denser star field.  The part of the Milky Way we are looking at here is the Sagittarius arm of the galaxy that sits between us and the center of our galaxy.  Many of the stars you will be able to see in binoculars lie at distances between 6,500 and 13,000 lights years away.  Even in light polluted skies there are thousands of stars scattered in this relatively small patch of sky. 

Getting out to dark skies is where you will see why these structures are called star clouds.  With just the unaided eye the dense fields of these relatively dust free windows into the depths of the Milky Way will be much brighter than the rest of the dust obscured parts of our galaxy’s concentration.  The glow you see here is representative of millions of stars that lie closer to the Milky Way’s core than we do. 

Once you have scanned and taken in the entire star cloud there are a number of other objects that stand out in the same area.  M7 or Ptolemy’s cluster is an open cluster that is much closer to us than the GSSC is.  It will be easily seen as a bright group of roughly 80 stars on the southern boundary of the star cloud.  At only 800 light years away this group of stars is in the same arm (Orion Spur) of the galaxy that the Sun is.  On the north edge of the GSSC is a bright emission nebula called M8 or the Lagoon Nebula.  This is an area where stars are actively forming that lies at about 5,200 light years away.  This stellar nursery is part of the Sagittarius arm of our galaxy and can be easily spotted with small binoculars.  In fact if you scan north of M8 you will find three more nebulae that are also in the Sagittarius arm.  These are named M20, M17 and M16. 

In addition to these nebulae there are a number of open star clusters scatter around the GSSC that can be seen but many will go unnoticed if you just quickly scan through the sky.  Most of the cluster will be around 8th or 9th magnitude and contain fewer than 100 stars. 

To get as much out of the GSSC you will need to spend some quality time soaking in the light for these distant stars.  I would recommend starting with binoculars no larger than 10 x 50.  There will be numerous double stars to identify and a hand full of deep sky objects as well.  Having a desktop planetarium software handy will help you identify some of these but a more detailed database will be required for fainter less obvious objects.  Below you will find basic maps of Sagittarius and Scorpius that will aid you in finding the GSSC and the brighter deep sky objects listed above. 

http://www.iau.org/static/public/constellations/gif/SGR.gif

http://www.iau.org/static/public/constellations/gif/SCO.gif

The star cloud for August 11 is called the Small Sagittarius Star Cloud (SSSC).  Even though the name implies it is lesser in nature this is the densest and my favorite of the star clouds we will look at this month.  The SSSC is also known as M24 as it was one of the objects Charles Messier included in his famous catalog.  Messier described it as a patch of nebulous light with numerous intertwined stars of different magnitudes. 

The SSSC spans about 1.5 degrees of the sky and provides us with a view of stars that fills a volume of the galaxy extending about 16,000 light years deep.  Like last week’s star cloud the SSSC provides us with an unobscured view into the depths of the Sagittarius arm of the Milky Way.

In light polluted skies where the dim glow of the Milky Way cannot be seen the SSSC looks like a collection of bright stars that are organized into long chains and arches.  All together I think they look like an umbrella that has been turned out by strong winds.  It is a very nice view that contains a number of bright stars many of which are double stars. 

Getting out to a dark site where the dim glow of the Milky Way is visible the SSSC will appear as a detached and brighter portion of the Milky Way.  The SSSC is best viewed through binoculars or small telescopes with wide fields of view.  Larger instruments will typically limit your field of view only allowing you to see small portions of the star cloud.  On a clear night using a good solid tripod it is easy to get lost in the myriad of stars in this dense part of the Milky Way.  Once you have spent some time scanning the star cloud there are a number of smaller deep sky objects to look for in the same part of the sky.  The most obvious will be an open star cluster called NGC 6603.  This 11th magnitude cluster will be a fine target in larger binoculars and small telescopes.  In addition to NGC 6603 you may notice two large dark patches in the SSSC.  These are dark nebulae known as B92 and B93.  These are large clumps of dust that block out the light from background stars.  Beyond these more obvious objects there are a number of less obvious clusters, a number of double stars and a planetary nebula to look for using moderate sized telescopes.  For an object that only spans 1.5 degrees of the sky it is densely packed with loads of goodies that will keep you occupied for a long time. 

To find the SSSC look for the teapot shape of Sagittarius described last week.  Using binoculars scan north of the teapot’s top and you will easily identify the compact dense star field of the SSSC.  Below you will find links to a map that will help you locate this object and additional information about the SSSC.  The linked IAU map for Sagittarius does not label the SSSC (M24) but it is located near a star called Mu Sagitarii.  This star will be marked on the map.

http://www.iau.org/static/public/constellations/gif/SGR.gif

http://messier.seds.org/m/m024.html       

Our next Star Party will be held on Friday, September 5, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on September 5, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m. 

This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org

Week of Monday, July 28

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, July 28.  All times are given as local St. Louis time (Central Daylight Time).  For definitions of terminology used in the night sky update, click the highlighted text.

Information updated weekly or as needed.

Join us for our next star party, Friday, August 1, 2014 held in association with the St. Louis Astronomical Society. For details, see the information at the bottom of this page.

The Sun and the Moon

Sunrise is at 5:59 a.m. on Monday, July 28 and sunset is at 8:15 p.m. providing us with about 14 and one half hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about 2 hours.  This period of time is called twilight, which ends around 10:02 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 1:08 p.m. this week.   

Moonrise for Monday, July 28 occurs at 7:39 a.m.  Moonset will occur at 8:59 p.m.  On Monday, July 28 the Moon will be exhibiting a waxing crescent phase with roughly 3% of the lunar disk illuminated.  First qaurter moon occurs on August 3 this week at 7:50 p.m.      

International Space Station (ISS) Observing

This week visible passes of ISS will be in the early morning and evening hours.  The best of these will occur on August 1 and 3.  To learn more about this pass and others this week use the information below.

Catch ISS flying over St. Louis in the morning and evening hours starting Monday, July 28. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

30 Jul

-0.9

05:09:15

10

NNW

05:12:09

26

NNE

05:15:03

10

E

31 Jul

-0.3

04:20:42

10

NNW

04:23:10

19

NNE

04:25:38

10

ENE

01 Aug

-2.7

05:08:02

10

NW

05:11:22

64

NE

05:14:42

10

ESE

01 Aug

-1.3

21:49:20

10

SSW

21:50:19

18

SSW

21:50:19

18

SSW

02 Aug

-1.7

04:19:20

10

NW

04:22:29

37

NNE

04:25:38

10

ESE

02 Aug

-2.1

21:01:05

10

S

21:03:47

23

SE

21:06:31

10

ENE

02 Aug

-1.7

22:37:16

10

W

22:40:22

35

NNW

22:41:14

30

N

03 Aug

-0.9

03:30:42

10

NNW

03:33:32

24

NNE

03:36:21

10

E

03 Aug

-2.9

05:07:10

10

WNW

05:10:21

41

SW

05:13:31

10

SSE

03 Aug

-2.8

21:48:11

10

WSW

21:51:29

60

NW

21:54:47

10

NE

Magnitude (Mag): The Measure of brightness for a celestial object.  The lower the value is, the brighter the object will be.

Altitude (Alt):  The angle of a celestial object measured upwards from the observer’s horizon.

Azimuth (Az):  The direction of a celestial object, measured clockwise from an observer’s location with north being 0°, east being 90°, south being 180° and west being 270°.

For information about ISS flyovers and other visible satellites, visit www.heavens-above.com

Detailed information regarding all unmanned exploration of our universe, missions past, present, and planned, can be found at Jet Propulsion Laboratories:

http://www.jpl.nasa.gov/

The Planets Visible Without A Telescope

Venus

Venus is now well within its current morning apparition. It rises around 4:09 a.m. becoming easily visible by 4:40 a.m.  Venus is currently exhibiting a gibbous phase with roughly 60% of the Venusian disk illuminated.

Mars

Mars is now in the constellation Virgo and rises before the Sun sets.  For those awake around 9:00 p.m. you will see a reddish-orange object high in the southern skies.  We have now passed by Mars in our orbit and will continue to move further away each day.  Mars will set by 11:47 p.m. 

Saturn

Saturn will be visible about 20 minutes after sunset.  Look for it in the south next to Mars which will be visible around the same time.  Saturn will remain with us until 12:48 a.m.  Saturn can found near the bright double star Zubenelgenubi.    

Keep an eye on Mars and Saturn as the two are approaching each other in the sky.  Later this year Mars will pass Saturn on its way into the constellation Scorpius. 

Constellation of the Month

Each month we will highlight one constellation and some of the objects that can be found within the boundaries of that constellation.  At the start of the month we will list only a few of these objects and each week we will add another to the list.  Some objects will be visible to the unaided eye and some may require a telescope.  Many of the objects listed will require a map of the sky to find or may require repeat observations to notice various properties.  Links to star charts and other information that will be useful in identifying the objects listed will be given at the end of each week’s section. 

For July will explore objects in the constellation called Lyra the Harp.  This constellation is one of those that are part of the bright asterism known as the Summer Triangle.  It contains the bright star Vega which is one of the three stars that make the bright triangle.  The Summer Triangle acts as a beacon for observers during the summer months helping us find other constellations and the objects they contain.  Due to the visibility and usefulness of the triangle, the constellation Lyra is one of the first visited by many observers during the summer months. 

The ancient Greeks imagined this small bright grouping of stars as the lyre that Apollo gave to his son Orpheus.  After the death of his wife Eurydice, Orpheus played his lyre impressing Hyades the god of the underworld.  Hyades was so impressed that he allowed Eurydice to follow Orpheus out of the underworld provided that Orpheus not turn back and look at her until they were safely out.  Orpheus at the last minute could not resist and when he turned back to look she was gone forever.

Lyra is also the home of one of the best meteor showers we see every year.  The Lyrid meteor shower is caused as the Earth annually plows through debris left by Comet Thatcher.  The first recorded observation of this meteor shower dates back to 687 BCE when Chinese astronomers recorded what appeared to be stars falling out of the sky in April.  April is the peak month to view the Lyrids with a peak date of April 22.

http://meteorshowersonline.com/lyrids.html

The crown jewel of Lyra is the bright star Vega.  This beautiful star is an A-class star meaning it will appear blue white in color.  The temperature of Vega is about 9,600 Kelvin making it about 1.7 times hotter than the Sun.  It is only twice the mass of the Sun but because of its higher temperature it is about 40 times more luminous.  This makes Vega one of the most luminous stars in the Sun’s galactic neighborhood.  As Vega is more massive and hotter it will only exist about one tenth as long as the Sun.  That is the nature of the bigger and brighter stars. 

One interesting feature of Vega is its location along the path that the Earth’s northern axis follows during the precession of the equinoxes.  This process is caused because of the Earth’s oblate shape and the tidal forces applied to our planet by the Sun and Moon.  As a result of these two factors the Earth wobbles causing our axis to trace out a cone shape.  This changing orientation causes the north polar axis to be orientated towards different stars.  We do not have to worry about a changing North Star as the precession process takes 26,000 years to complete one full wobble.  This equates to about one degree of motion per year.  In about 12,000 years Vega will become the Earth’s North Star. 

To find Lyra and its crown jewel all you have to do is look east about 45 minutes after sunset.  Doing this you will see three bright stars which form the Summer Triangle asterism mentioned above.  The other two stars in the triangle are called Denib and Altair.  As twilight begins to fade you will notice a parallelogram shape of stars just below Vega.  This is the main pattern people use to identify Lyra the Harp. 

http://www.iau.org/static/public/constellations/gif/LYR.gif

The first object we will cover in Lyra is the beautiful planetary nebula called M57 or the Ring Nebula.  Planetary nebulae are the remnants of stars like the Sun as they begin to evolve.  The Sun and all stars start out fusing the hydrogen at their cores.  From this process atoms of helium are produced along with some energy which eventually becomes the light we see emitted by stars.  Like our cars or any device that consumes a material component it will eventually run out of this “fuel” source.  Once the Sun runs out of its core hydrogen its core will begin to collapse and the outer layers will expand and cool.  Due to its collapse core temperature will rise until the helium that has been collecting at the core begins to fuse.  Again the core will run out of its “fuel” and collapses until it is hot enough that carbon and oxygen can fuse.  This stage is called a white dwarf and it is where most stars will end their stellar lives. At this stage all that is left is a much smaller but hotter core.  For a brief time this high temperature allows the dying star to excite the gasses around it creating a beautiful fluorescing cloud of gas and debris.  This is what is called a planetary nebula.  When we observe M57 we are looking at the Sun’s distant future. 

To find M57 first locate the star Vega and the parallelogram shape below it.  Once you have identified the parallelogram shape of stars you need to identify the two southern most stars in this shape.  They are named Beta and Gamma Lyrae.  Using a telescope scan between these two stars and you will find a distinct ring shaped source of light.  This is the planetary nebula M57. 

M57 shines with a magnitude of 8.8 which means it is dim enough that we do need a telescope to observe it.  It is possible that big binoculars will spot it but M57 is roughly one arc minute across causing it to appear very small through wide field devices.  Because of this giant binoculars that have the resolving power to see this nebula would only reveal a small star like object.  If you do not have your own telescope, look up your local astronomy clubs.  Astronomy clubs, museums and many universities will host observing nights that are free to anyone.  Here in St. Louis we have three active astronomy clubs.  All three of them host numerous observing nights one of which is our First Friday observing program.  Below you will find links to the astronomy clubs in St. Louis and more information about M57.

http://www.iau.org/static/public/constellations/gif/LYR.gif

http://messier.seds.org/m/m057.html

http://www.slasonline.org/

http://www.asemonline.org/

http://stemideas.org/outreach-projects/star-gazing/

The object for the week of July 7 is the star Delta Lyrae.  There are a few reasons I wanted to cover this star in the night sky update.  First it is a double star.  Unlike those in the past this double is not physically a pair but rather is called an optical double.  These two stars happen to appear close together but are actually about 200 light years apart.  Frequently you will see them listed as Delta-1 and Delta-2.  Delta-1 is a bright B-Class hydrogen fusing star that has a temperature of 18,000 Kelvins.  This puts Delta-1 at nearly 3000 times hotter than the Sun.  Delta-2 is about 200 light years closer to us and is an M-Class red giant star.  Delta-2 is about 7 times more massive than the Sun and is about 300 times larger than the Sun. 

The bright red color of Delta-2 and the blue color of Delta-1 give the pair a very nice color contrast making them an attractive pair to seek out.  In addition to the color contrast Delta-1 is a member of an open star cluster called Stephenson 1.  This is a cluster that is not very well detached from the background stars and it has less than 50 component stars. 

In addition to Delta-1 & 2 you can also try to find another red star called SAO 67546.  This is another member of the Stephenson 1 cluster that is a K-class red giant star that will have an orange hue.  Both Delta-2 and SAO 67546 are stars on their way to becoming white dwarfs that could produce planetary nebulae like M57 discussed last week. 

To find the optical double star Delta Lyrae and the associated Stephenson 1 star cluster first find the bright star Vega.  Once you have identified Vega look for the parallelogram shape of stars below the bright star described last week.  This time we want to use the northern two stars of the parallelogram shape.  These stars are called Zeta and Delta Lyrae.  The latter of the two being our target star. 

Those with sharp vision will be able to determine that Delta Lyrae is two stars.  The distinct color of the two stars and the Stephenson 1 cluster can be seen clearly through a simple pair of binoculars.  The best view of the cluster will be through a telescope using a low magnification eyepiece.  Reference the map linked below for help finding Delta Lyrae and the associated Stephenson 1 star cluster.

http://www.iau.org/static/public/constellations/gif/LYR.gif

The object for the week of July 14 is the multiple star system Epsilon Lyrae.  What looks to be a 4th magnitude star near Vega is really the combined glow of four separate stars.  Last week we covered a similar multiple star called Beta Lyrae but Epsilon is different in that its member stars are gravitationally bound to one another.  In other words Epsilon Lyrae is a binary system.  Careful inspection of Epsilon Lyrae will reveal two stars using just your eyes.  For those of us with less than perfect vision a pair of binoculars will plainly reveal what looks like two bright white stars.  The western of the two is Epsilon 1 and the eastern of the two is Epsilon 2.  Epsilon 1 and 2 are separated by roughly 10,000 AU (AU = 93 million miles; average distance between Earth and Sun) and are estimated to take nearly 400,000 years to orbit each other. 

Using a decent telescope at moderate magnification Epsilon 1 and 2 can each be split into two stars.  Splitting Epsilon 1 and 2 is easy because they are about 200 seconds of ac apart.  Splitting the two pairs is a bit more difficult because they are only a few second of arc apart.  A moderate sized telescope will work you will just have to bump up the magnification.  The Epsilon 1 pair is labeled 1A and 1B and the Epsilon 2 pair is labeled 2C and 2D.

All four stars are A-class stars with temperatures that range from 7700 kelvins to 8200 kelvins.  At these temperatures the stars shine with a white to bluish white color.  The stars have masses at 1.9, 1.5, 1.9 and 1.8 solar masses making them main sequence white dwarf stars. These are not the same as the white dwarf discussed above with M57.  The white dwarf related to M57 is a highly evolved star that has shed its outer layers revealing a small dense core that is fusing carbon and oxygen.  Main sequence white dwarfs are young hydrogen fusing stars that are still in their prime.

The stars in the Epsilon Lyrae system are approximately 800 million years old.  For the time being they are gravitationally bound but as they move through the Milky Way the pairs will likely separate into two separate double star systems.  Finding Epsilon Lyrae is pretty simple as it is right next to the bright star Vega.  Once you find Vega all you have to do is look about 2 degrees to the east and you will see Epsilon Lyrae.  If you deal with light pollution or diminished vision you will likely need binoculars to spilt the wide pair.  To spot all four stars you will need a telescope.  Depending on how large your telescope is you will need moderate to high magnification to split all four.  If you have an interest in finding more double or multiple star systems there are numerous other options this time of year.  Sky and Telescope has some very nice articles that will help you find many more doubles and more importantly help you refine your observing skills that are required to find and observe this type of object.  Below you will find links to these articles and the IAU map of Lyra.

http://www.iau.org/static/public/constellations/gif/LYR.gif

http://www.skyandtelescope.com/observing/celestial-objects-to-watch/double-stars/  

The object for the week of July 21 is the globular star cluster Messier 56 (M56).  This globular star cluster is a member of the Milky Way’s outer halo of globular star clusters.  It was likely captured by the Milky Way as it consumed one of its dwarf galaxies.  M56 lies about 32,900 light years away from us and is moving towards us at a rate of 145 km/s.  M56 likely has around 50,000 stars as its mass is thought to be 230,000 times that of the Sun.  The stars in M56 are estimated to be about 13.7 billion years old.  Stars this old started to form shortly after the universe expanded into its current state.

At magnitude 8.3 it is one of the fainter globular star clusters included in the Messier catalog.  Even so it can be seen through 50mm binoculars or small aperture telescopes.  When viewed through these instruments M56 will appear as a faint out of focus star.  If you are having trouble seeing the faint glow from these stars try slightly moving your instrument back and forth and this will often help the eye detect the faint light.  Telescopes that are 8 inches or larger will begin to resolve the brightest stars in M56.

Finding M56 is relatively simple as it lays between the two bright stars Gamma Lyrae and the famous double star Alberio in Cygnus the Swan.  If you start at Gamma Lyrae and head towards Alberio you will find an arrow shaped group of stars that will point you towards M56.  M56 is about half way between the two bright stars listed above. 

http://www.iau.org/static/public/constellations/gif/LYR.gif

http://messier.seds.org/m/m056.html

The final object we will cover in July is the star Beta Lyrae.  Also known as Sheliak this is normally a 3.52 magnitude star that has a B-spectral class making it blue in color.  It is about 90 times brighter than the Sun and is about 13 times more massive.  Sheliak lies about 960 light years away.

Sheliak is interesting for a number of reasons.  It is a multiple star system, it changes its brightness making it a variable star and it is one of the more distant bright stars we can easily see with the naked eye.  There are many reasons to observe this star but its variable nature is the primary reason.  Sheliak is an eclipsing binary system.  It has two stars that happen to orbit in such a way that their orbital plane is nearly parallel to our line of sight.  Simply put they pass in front of one another.  This happens on a cycle of roughly 13 days.  At about 3 days into the cycle the secondary star eclipses the primary.  By about day 10 the primary will eclipse the secondary.  The first eclipse that occurs is the most dramatic dropping the magnitude of Sheliak by about one order of magnitude.  The secondary eclipse only drops the magnitude of Sheliak by about half a magnitude order. 

The primary eclipse is more dramatic due to the secondary star being larger and it contains an accretion disk.  The disk is comprised of material that it has stolen from its now smaller companion.  At one point the primary star in this pair was the more massive and larger of the two.  It started to evolve into a giant star allowing it to exceed its Roche Lobe.  When a star fills its Roche lobe, material gravitationally bound to the star can escape out into space or in the case of a binary system can transfer to the partner star leading to an accretion disk.

When all is said and done roughly every 13 days you will notice Sheliak dim down to about 4.3.  Sheliak will slowly dim down to its minimum magnitude of 4.3 which occurs on day three of the cycle.  It will take another three days to reach it maximum magnitude of 3.4.  The three day cycle continues bringing Sheliak’s magnitude down to about 3.8 magnitude for the lesser eclipse and then back up again three days later.  Tracking variable stars can be a challenge but as long as you establish some reference stars this variable should be pretty easy for most to follow. 

To find Sheliak locate Vega.  Below it you will find the parallelogram shape of stars discussed in previous weeks.  The southern and eastern most of the four stars in the parallelogram shape is the star Sheliak.  Every night over a period of about 13 days go outside once twilight has ended and make an estimate for Sheliak’s magnitude.  If you do this often enough it will become easy to identify the maximum and minimum for this bright star.  Reference the links below to learn more about this star.

http://www.iau.org/static/public/constellations/gif/LYR.gif

http://www.aavso.org/vsots_betalyr

Our next Star Party will be held on Friday, August 1, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the Science Center will set up a number of telescopes outdoors and be on-hand to answer your questions.  Telescope viewing begins at 8:00 p.m.  Regardless of the weather on August 1, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.
This free, indoor star program will introduce you to the current night sky, the planets, and the seasonal constellations. Doors open 15 minutes before show time. Shows begins at 7 p.m. Sorry, no late admissions due to safety issues in the darkened theater.

The St. Louis Astronomical Society hosts the monthly Star Parties at the Science Center which are held on the first Friday of each month. Our Monthly Star Parties are open to the public and free of charge.  For more information about the St. Louis Astronomical Society visit their website at www.slasonline.org