NIGHT SKY UPDATE for the week of Tuesday, April 26, 2016

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Tuesday, April 26.  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, May 6, 2016 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 6:09 a.m. on Tuesday, April 26 and sunset is at 7:49 p.m. providing us with roughly 13.5 hours of daylight.  Even after sunset, the light from the Sun will still dimly illuminate our sky for about one hour and forty minutes.  This period of time is called twilight, which ends around 9:28 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 12:59 p.m. this week.   

Day

Sunrise

Sunset

26 Apr

6:09 a.m.

7:49 p.m.

27 Apr

6:08 a.m.

7:50 p.m.

 28 Apr

6:07 a.m.

7:51 p.m.

 29 Apr

6:05 a.m.

7:52 p.m.

 30 Apr

6:04 a.m.

7:53 p.m.

 01 May

6:03 a.m.

7:54 p.m.

 02 May

6:02 a.m.

7:55 p.m.

 03 May

6:01 a.m.

7:55 p.m.

 04 May

6:00 a.m.

7:56 p.m.

           

Moonrise for Tuesday, April 26 occurs at 11:51 p.m. and moonset will occur at 10:08 a.m. on the following day.  On April 26 the moon will be exhibiting a waning gibbous phase with about 82% disk coverage. Last quarter moon occurs on April 29.    

International Space Station (ISS) Observing 

There are no visible passes of ISS from St. Louis this week.  There are however some nice passes of the Chinese space station Tiangong 1.  They occur on the mornings of May 1, 2 and 3.  ISS will return to St. Louis skies on May 6.  

Catch Tiangong 1 flying over St. Louis in the morning hours starting Tuesday, April 26.  

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

01 May

 1.9

04:40:23

15

WNW

04:42:44

49

NNE

04:45:47

10

E

02 May

 1.0

05:16:14

10

WNW

05:19:20

71

SSW

05:22:25

10

ESE

03 May

 1.2

04:18:16

41

NW

04:19:10

70

NNE

04:22:16

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

Mercury

The elusive planet is nearing the end of another evening apparition.  You can find Mercury about 7 degrees above the western horizon 45 minutes after sunset.  Mercury will set soon after at 9:11 p.m.  This is the last week to see Mercury after sunset. 

On Monday, May 9 Mercury will reach inferior conjunction.  This time Mercury will pass directly between us and the Sun allowing Mercury to transit across the visible disk of the Sun.  Mercury will appear as a small black dot passing in front of the Sun and can only be observed if you use safe solar filters.  The transit begins May 9 at 6:13 a.m. and ends at 1:41 p.m.  If weather permits the Saint Louis Science Center will have free viewing of this event starting at 9:30 a.m.  Follow the link below for more information.  

http://www.slsc.org/Transit-of-Mercury

http://eclipse.gsfc.nasa.gov/transit/transit.html

Mars

The Red planet is currently found in Ophiuchus rising at 10:18 p.m.  By 11:00 p.m.  Mars will be easily seen in the southeastern sky.  Mars will continue to climb higher in our sky as we approach May 22, 2016 which is the next opposition of Mars.  Mars is back and getting better once again.  

Jupiter

Jupiter now rises before the Sun sets. To see Jupiter you will have to look east at about 8:15 p.m.  Jupiter sets at 4:08 a.m.  Each week Jupiter will set approximately 30 minutes earlier than it did the week before. 

Saturn

The ringed planet has started another apparition and can be seen in the twilight hours before sunrise.  Saturn rises at 10:46 p.m. and can be seen low in the southeast around 12:00 a.m.   

Deep Sky Object of the Week

A few years ago the night sky update included a section that highlighted one constellation a month and a few objects of interest inside of it.  Unfortunately of the 88 constellations there are only about 60 we can see in St. Louis and of these there are only so many that have enough objects to reference that would interest both beginners and advanced observers.  In 2015 we changed things a bit for this section and instead of highlighting one constellation for each month we highlighted one Messier object a week using the Astronomical League’s Binocular Messier program as our guide.  We will continue this into 2016 but instead of using the Astronomical League’s binocular Messier program we will use their Binocular Deep Sky Program.     

The Astronomical League is an amateur astronomy society that is composed of over 240 local amateur astronomy societies across the United States and includes members at large and other supporting members.  Their goal is to promote the science of astronomy through education, incentive and communication.  

One of the many ways the Astronomical League has assisted amateur astronomers around the world is by creating various observing programs that highlight different aspects of astronomy and how an amateur astronomer can observe the sky and learn more about astronomy in doing so.  Some of these programs are introductory and are targeted at those beginning to learn about observational astronomy and some are extremely advanced, require specialized equipment and require a large amount of time to complete.  These observing programs cover most any type of object or way to observe the sky so everyone should be able to find one that matches their interests and abilities.  It is important to note that these programs are not part of any class or lecture series but are rather lists of objects that highlight types of objects or observing methods relevant to astronomy.  Taking part in these programs is done under one’s own choice.  To officially complete each program you do have to be a member of the Astronomical League but you do not have to join to use them as observing guides or education tools.  I would urge anyone interested in astronomy to look at these programs as they will help organize observing sessions and will help refine observing skills you already have.  You can find out more information about the Astronomical League’s observing programs here https://www.astroleague.org/observing.html 

The observing program we will use to help guide us through the 2016 observing year is the Binocular Deep Sky Program.  This is a program that will appeal to both beginning and advance observers.  Too often it is thought that you need to have a telescope for astronomical observations.  Telescopes make great observing tools and yes they can show you more than binoculars but they do have their limitations.  Cost, size, weight and complexity will often be a surprise to people when they first learn about telescopes.  These factors can keep people from using telescopes they own or from buying one at all.  The best advice to follow is a good observing tool is one you will use.  

The binocular deep sky program is an introduction to deep sky objects beyond the Messier catalog.  It will introduced viewers to the New General Catalog (NGC) and some of the lesser known deep sky catalogs such as the Stock, Collinder and Melotte.  Each week we will highlight a deep sky object that is part of the Astronomical League’s binocular deep sky program.  This program is tougher than Messier binocular program as the objects are not always as obvious and they will require larger binoculars than the Messier program.  50mm binoculars are recommended but many of the targets can be seen through smaller aperture instruments.  I would urge each observer to fulfill the requirements of the program even if you do not intend to join the League for completion.  The requirements involve logging observing data that can help refine observing skills that will be useful later down the road.  If you have an interest in astronomy and learning more about observational astronomy I would also recommend checking out one of the two excellent astronomy societies near St. Louis.  Both are members of the Astronomical League and both do numerous public observing nights around town.  These clubs are the

St. Louis Astronomical Society and

Astronomical Society of Eastern Missouri

If you do not live in the St. Louis, Missouri area chances are you have similar astronomical societies where you live.  

The deep sky object for the week of March 29 is the open star cluster NGC 2244.  At a distance of roughly 5,000 light years NGC 2244 shines with an apparent magnitude of 4.8.  The stars in this cluster are thought to be less than five million years old and are associated with the emission nebula called the Rosetta Nebula.  This glowing cloud of gas is excited by the hottest and most massive stars in NGC 2244 with the two main culprits being HD 46223 and HD 46150.  These two O-type stars are extremely hot and are respectively 400,000 and 450,000 times brighter than the Sun.  They are also much more massive at 50 and 60 times more massive.  These stellar monsters are very turbulent stars that produce strong solar winds which in turn excites the surrounding gas cloud.  Unfortunately the Rosetta nebula is not visible through binoculars. 

The Trumpler classification for NGC 2244 is II, 3, p, n which means it is a detached cluster with little central concentration, it is composed of both bright and dim stars, it is a poor cluster with 50 or less members and it is associated with a nebula. 

To find NGC 2244 you will need to locate the constellation Monoceros.  To do this start by locating the constellation Orion.  He will be located in the southwest around 9:00 p.m.  Once here locate the bright red supergiant star Betelgeuse in Orion’s shoulder.  From here scan to west about 20 degrees and you will find the bright star Procyon in Canis Minor.  Using Betelgeuse and Procyon as your guides, scan about 1/3 of they between them starting from Betelgeuse and you will find Monoceros and NGC 2244.  Use the maps below for help in locating this star cluster. 

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

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

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

The deep sky object for the week of April 5 is the open star cluster NGC 2251.  This open star cluster is a group of roughly 30 stars that are estimated to be 300 million years old.  At a distance of roughly 5,000 light years NGC 2251 shines with an apparent magnitude of 7.3.  The Trumpler classification for NGC 2251 is III, 2, p which means it is detached from background stars but has no central concentration, its stars have a moderate range in brightness and it is a poor cluster with less than 50 members.  

To find NGC 2251 you will have to locate the constellation Monoceros.  To do this you will want to use the same methods we used last month to find NGC 2244.  Once you have located last week’s target you will want to scan north about five degrees.  NGC 2251 will be a challenge because it is in a crowded part of the sky.  So take your time and find the best star map you can.  As a start you can use the maps below but I would recommend finding a better one or use a desktop planetarium software such as Stellarium.  If you use the first map ignore the red arrow on it.  NGC 2251 can be found at the bottom of the map.

https://upload.wikimedia.org/wikipedia/commons/thumb/8/89/NGC_2169_map.png/440px-NGC_2169_map.png

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

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

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

The deep sky object for the week of April 12 is the open star cluster NGC 2264 which is found in the constellation Monoceros.  This open cluster of stars shares its NGC designation with another object called the Cone Nebula.  The Cone Nebula is associated with the star cluster but it requires dark skies and a 10 inch aperture telescope to see.  NGC 2264 is a group of 40 stars that are thought to be about 20 million years old.  At a distance of roughly 2,400 light years NGC 2264 shines with an apparent magnitude of 3.9.  The brightest star in the cluster is called 15 Monocerotis (15 Mon) or S Monocerotis (S Mon) which has an apparent magnitude of 4.66.  NGC 2264 is surrounded by a dim emission nebula that can partially be seen through a telescope.  The nebula is a cloud of hydrogen and dust particles that is excited by ultraviolet radiation from 15 Mon.  NGC 2264 has a Trumpler classification of IV, 3, p, n; which means it is not detached from background stars, it is composed of both bright and faint stars, it is a poor cluster with less than 50 members and it is associated with a nebula.   

To find NGC 2264 you need to find the constellation Monoceros which can be found just east of the star Betelgeuse.  First start by replicating what was done last week to find the star cluster NGC 2251.  Once you are there you will want to scan four degrees to the northeast and you will be in the right area.  NGC 2264 is also known as the Christmas Tree cluster due to its shape.  Look for this shape with the brightest star 15 Mon being the trunk of the tree.  Use the maps below for help finding NGC 2264.

http://www.backyard-astro.com/focusonarchive/monoceros/Monoceros.gif

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

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

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

The deep sky object for the week of April 19 is the open star cluster NGC 2281.  This star cluster contains approximately 30 stars that are estimated to be about 300 million years old which is around the time the supercontinent Pangaea formed on the Earth.  At a distance of 1,600 light years NGC 2281 shines with an apparent magnitude of 5.4.  NGC 2281 has a Trumpler classification of I, 3, p which means it is well detached from background stars with a strong central concentration, it has a wide range in stellar magnitudes and it is a poor cluster with less than 50 stars. 

NGC 2281 can be found in the Constellation Auriga which is seen in the northwest by 9:00 p.m.  To find Auriga you will want to start by finding Orion’s Belt.  Once here imagine it as an arrow pointer with the three belt stars as one half of the arrow head.  Follow the direction it points to the north and you will find the bright star Capella.  From here follow a path from Capella to the star Menkalinan and continue beyond another 10 degrees.  Here is where you will find NGC 2281 which will appear as scattered group of bright stars.  Follow the links below for help in finding NGC 2281 or use the free planetarium software Stellarium.  

https://en.wikipedia.org/wiki/NGC_2281#/media/File:NGC_2281_map.png

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

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

The deep sky object for the week of April 26 is the open star cluster NGC 2301.  Found in the constellation Monoceros, NGC 2301 contains about 80 members that are estimated to be 110 million years old.  At a distance of 2,500 light years it shines with an apparent magnitude of 6.0.  It has a Trumpler classification of I, 3, m which means it is well detached from background stars with a central concentration, it has a wide variance in stellar magnitudes and it is a medium rich cluster with between 50 and 100 stars.  

To find NGC 2301 start by location the constellation Orion around 9:00 p.m. low in the west.  Using the stars Lambda Orionis and Betelgeuse star hop between them moving from Lambda to Betelgeuse.  Continue following the same path these stars create and you will come across three bright stars in Monoceros starting with 8 Mon then 18 Mon and eventually Delta Mon.  These stars will be successive steps of 7 degrees from each other.  Once you find these stars look about 2.5 degrees southeast of 18 Mon and you will find NGC 2301.  For help in finding NGC 2301 use the maps below. 

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

http://www.astronomy.com/-/media/Images/Multimedia/Podcasts/Monoceros.jpg?mw=600

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

Our next Star Party will be held on Friday, May 6, 2016, from dusk until 10 p.m. 

As part of the Saint Louis Science Center’s First Fridays, 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 around 7 p.m.  Regardless of the weather on May 6, 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 helps host the monthly Star Parties at the Saint Louis 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.  

The Ultimate Interactive Flight Exhibition

Come celebrate aerospace technology with this new highly interactive special exhibition. Above and Beyond features simulations that allow visitors to design and test-fly a supersonic jet, experience flight as a bird, and ride in a space elevator.  This special exhibition will immerse you in flight and space travel.

Miles from Tomorrowland

Calling all Cosmic Explorers! Disney Junior and the St. Louis Science Center invite you to the Miles From Tomorrowland Space Missions experience. Join us in the Discovery Room and explore tech, vehicles and planets with fun mission activities every day this summer starting July 20th – August 31st. Join us for a blastastic time!

Plus, you can submit a photo of your child’s activity online for a chance to win the XPRIZE Superstellar Blast Off Experience including: a VIP family trip to the Kennedy Space Center to see a rocket launch and meet an astronaut. Winners will also receive a virtual reality viewer, 3D printer and Miles From Tomorrowland toys!  Visit DisneyJunior.com/SpaceMissions for more information. 

 

NO PURCHASE NECESSARY. Void where prohibited. Open to persons who are, as of entry, 18 years of age or older, or the age of majority, whichever is older, and legal residents of, and physically located within, the 50 United States or D.C. Limit one (1) Submission per Member per day. Contest begins at 12:01 AM (PT) on July 15, 2015, and Submissions must be received by 11:59 PM (PT) on August 31, 2015. Click here for Official Rules for full eligibility and entry details. 

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

Week of Monday, July 21

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, July 21.  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 5:53 a.m. on Monday, July 21 and sunset is at 8:21 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 10:11 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 1:07 p.m. this week.     

Moonrise for Monday, July 21 occurs at 1:44 a.m.  Moonset will occur at 4:04 p.m.  On Monday, July 21 the Moon will be exhibiting a waning crescent phase with roughly 24% of the lunar disk illuminated.  New moon occurs on July 26 this week at 5:42 p.m.      

International Space Station (ISS) Observing

This week visible passes of ISS will be in the early morning hours.  The best of these will occur on July 22 and 23.  To learn more about this pass and others this week use the information below.

Catch ISS flying over St. Louis in the morning starting Monday, July 21. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

22 Jul

-1.7

03:35:25

27

NW

03:35:39

28

NNW

03:38:37

10

NNE

22 Jul

-0.2

05:12:46

10

NNW

05:13:18

10

N

05:13:50

10

N

23 Jul

-1.0

02:48:35

25

NNE

02:48:35

25

NNE

02:50:17

10

NE

23 Jul

-0.4

04:23:02

10

NW

04:24:29

12

NNW

04:25:56

10

N

24 Jul

 0.1

02:01:44

11

NE

02:01:44

11

NE

02:01:52

10

NE

24 Jul

-0.7

03:34:36

14

NW

03:35:42

15

NNW

03:37:48

10

NNE

25 Jul

-0.7

02:47:43

19

N

02:47:43

19

N

02:49:35

10

NNE

26 Jul

 0.1

02:00:49

13

NNE

02:00:49

13

NNE

02:01:18

10

NNE

26 Jul

-0.1

03:35:11

10

NNW

03:35:54

11

N

03:36:36

10

N

27 Jul

-0.2

02:46:46

13

NNW

02:47:04

13

NNW

02:48:37

10

NNE

28 Jul

 0.1

01:59:50

13

N

01:59:50

13

N

02:00:27

10

NNE

28 Jul

-0.2

05:12:02

10

NNW

05:14:05

15

NNE

05:16:09

10

ENE

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 4:00 a.m. becoming easily visible by 4:30 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 12:09 a.m. 

Saturn

Saturn has reached opposition and thus will rise before the sun sets.  Look for it in the southeast about 30 minutes to an hour after sunset depending on how clear your southeastern skies are.  Saturn will remain with us until 1:16 a.m.  It forms a nice triangle in the sky with Libra’s two brightest stars Zubenelgenubi and Zubeneschamali. 

If you watch Saturn in relation to these two stars you will notice it is exhibiting retrograde motion.  This is caused as the Earth catches up with a planet and then passes it by.  During this we see the planet from changing angles making it appear to move westward and then eastward again. This motion is more prevalent with planets closer to us such as Mars.  If you go outside once a week for the rest of the year and sketch where Saturn is in relation to Zubenelgenubi and Zubeneschamli you will see this retrograde motion. 

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

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

Week of April 21, 2014

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, April 21.  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, May 2, 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 6:16 a.m. on Monday, April 21 and sunset is at 7:44 p.m. providing us with over 13 hours of daylight.  Even after sunset, the light from the Sun will still illuminate our sky for about one hour and 30 minutes.  This period of time is called twilight, which ends around 9:20 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, April 21 occurs at 1:13 a.m.  Moonset will occur at 11:44 a.m.  On Monday the 21st the Moon will be exhibiting a waning gibbous phase with 57% of the lunar disk illuminated.  Last quarter moon occurs on April 22.

International Space Station (ISS) Observing

The next visible passes of ISS over St. Louis are evening passes.  The best passes are on the evenings of April 21, 23 and 24.  Learn more about these passes and others this week in the table below.

Catch ISS flying over St. Louis in the evening hours starting Monday, April 21. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

21 Apr

-3.1

21:15:34

10

NW

21:18:54

62

NE

21:19:26

52

E

22 Apr

-2.3

20:27:05

10

NW

20:30:13

36

NNE

20:32:52

13

E

22 Apr

-0.9

22:04:06

10

WNW

22:05:45

19

WSW

22:05:45

19

WSW

23 Apr

-2.4

21:15:03

10

WNW

21:18:14

41

SW

21:19:10

32

S

24 Apr

-3.2

20:26:11

10

NW

20:29:32

80

SW

20:32:35

12

SE

25 Apr

-0.6

21:15:12

10

W

21:17:03

14

SW

21:18:54

10

SSW

26 Apr

-1.4

20:25:30

10

WNW

20:28:19

25

SW

20:31:07

10

S

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 4:34 a.m. becoming easily visible by 5:15 a.m.  For those awake at this time you will see Venus in the southeast and Saturn southwest.  This planetary display nicely represents the path that the planets, Sun and Moon follow.  This path is called the ecliptic.  Take a look at Venus through a telescope and you will see it is phased much like the Moon.  Venus is currently exhibiting a gibbous phase with roughly 63% of the Venusian disk illuminated.

Mars

Mars is now in the constellation Virgo and will rise around 6:07 p.m. this week becoming visible shortly after the Sun sets.  For those awake around 9:00 p.m. look to the east and you will see a reddish-orange object high in the southeastern skies. 

We have now passed by Mars in our orbit and will continue to move further away each day.  We probably have another month or so to view the surface of Mars through a backyard telescope.  Take a look at the red planet now for it will be another 26 months before we get this opportunity again.   

Jupiter

Jupiter will be visible high in the western skies roughly 30 minutes after sunset.  As twilight fades you will see the bright stars Castor and Pollux just east of Jupiter.  Looking at these stars and then comparing them to Jupiter you will see that the stars are twinkling and Jupiter is not.  The twinkling you see is called scintillation which is a distortion of the stars light by Earth’s atmosphere.  Testing for scintillation is how you can distinguish stars from planets.  Jupiter is currently in the constellation Gemini the Twins. 

Saturn

Saturn rises by 9:10 p.m. and will be an easy target by 10:00 p.m.  Saturn is currently in the constellation Libra.  It forms a nice triangle in the sky with Libra’s two brightest stars Zubenelgenubi and Zubeneschamali.  If you watch Saturn in relation to these two stars you will notice it is exhibiting retrograde motion.  This is caused as the Earth catches up with a planet and then passes it by.  During this we see the planet from changing angles making it appear to move westward and then eastward again.  This motion is more prevalent with planets closer to us such as Mars.  If you go outside once a week for the rest of the year and sketch where Saturn is in relation to Zubenelgenubi and Zubeneschamli you will see this retrograde motion.  As retrograde motion is occurring that also means we are approaching another opposition with Saturn.  This occurs on May 10th 2014.  As we approach this date Saturn will continue to get brighter in the sky. 

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 for the month of April is Camelopardalis.  This little known constellation is found in our circumpolar sky so it can be viewed throughout the entire year.  With such visibility it might seem odd that most have never heard of let alone seen this large northern constellation.  The brightest stars in Camelopardalis only reach 4th magnitude meaning that for city observers these stars may need a pair of binoculars to be seen.

Camelopardalis is considered a modern constellation having only been recognized for about 400 years.  It is usually referred to as the giraffe as its name means spotted camel.  It was introduced as a constellation in 1612 by Dutch astronomer and cartographer Petrus Plancius.  Along with this constellation he is responsible for helping map out constellations of the southern hemisphere and introducing a few other constellations still recognized today.

Owing to its dim nature Camelopardalis can be difficult to find particularly in light polluted skies.  The first thing to do is find the constellation Perseus and Auriga.  Camelopardalis is north of these two constellations.  Next find the bright star Capella in Auriga.  About 8 degrees north of Capella you will find the two brightest stars of Camelopardalis called Beta and Alpha Cam.  Unfortunately there is no distinct pattern that stands out in Camelopardalis so you will have to use the star chart below to find the rest of the constellation.  Camelopardalis is north of the constellations Draco, Ursa Major, Lynx, Auriga and Perseus.  Its western boundary is at Cassiopeia and its northern boundary is at Ursa Minor and Cepheus.  This will be a difficult constellation to find but it is worth the effort as it will be the source location for a new meteor shower that will peak this year on May 24.  As we approach this new and potentially amazing meteor shower I wanted to help prepare readers for this event by introducing them to the constellation that houses its radiant.  Before we cover the meteor shower I want to first take a tour of this often over looked constellation.

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

The first object we will explore in Camelopardalis is its brightest star Beta Camelopardalis.  Beta cam is a G-class yellow supergiant star that is in the process of evolving off of its main sequence into the red giant phase.  It has started to fuse the helium at its core which has allowed for its outer atmosphere to cool and begin expanding.  Beta Cam is at a point where it should begin to pulsate as a Cepheid variable but has yet to start the clockwork like pulsations.  At a distance of 1000 light years this giant star with a luminosity that is 3300 times that of the Sun only shines as a 4th magnitude star.  This is because of Beta Cam’s distance and the dimming caused by interstellar dust.  

Another strange feature of this star is it was observed to suddenly display a bright flash of light in 1967  This and the fact that Beta cam is an x-ray source indicates the star likely experiences magnetic upheaval much like our Sun.  It is possible that the bright flash seen by pilots in 1967 was caused by a magnetic reconnection event similar to a solar flare on the Sun.   

Beta Cam is also a multiple star system.  A small telescope and large binoculars will be able to resolve a fainter companion (B-component) that is separated by 83 arc seconds.  The primary yellow supergiant star shines at 4th magnitude and the fainter companion shines at 7.4 magnitude.  The fainter B-component is itself a double star.  Very little is known about the second star in the B-component system.

To find Beta Cam first locate the star Capella in the constellation Auriga.  From here scan about 8 degrees north until you find the next brightest star.  This will be Beta Cam.  This triple star system will be the easiest thing to find that we cover for this month’s constellation.  Due to dim nature of the Camelopardalis our ability to star hop will be tested.  Use the map below to find Beta Cam and start familiarizing yourself with the other stars of Camelopardalis.

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

The next object for the week of April 7 is the asterism known as Kemble’s Cascade.  Most of the objects we include in this section are cataloged objects that are normally some kind of star cluster, nebula or galaxy.  However there are some objects that are no more than a chance grouping or alignment of stars that stand out to observers and can be quite nice to look at.  One such asterism is known as Kemble’s Cascade.  This grouping of stars was discovered by an amateur astronomer named Lucian Kemble.  He was scanning Camelopardalis and noticed a string of stars that spanned about 2.5 degrees of sky.  It was later named in his honor and remains a popular target in the sparse constellation of Camelopardalis.

Kemble’s Cascade is a string of 20 stars, mostly 7th to 10th magnitude, which spans about 2.5 degrees.  The center of the string is accented with a 5th magnitude star.  The stars that make up Kemble’s Cascade are not related to each so what we see is just a chance alignment.  Following this cascade of stars to the southeast will bring us to an open star cluster called NGC 1502.  This cluster contains about 45 stars that will appear as a faint glow at the end of Kemble’s Cascade. 

To find Kemble’s Cascade start by locating Beta and Alpha Cam again.  From these two stars sweep about one binocular field to the west and you will see a line of stars that appear to cascade down from northwest to southeast.  This is Kemble’s Cascade.  Using the map linked below you will see a small curved grouping of four stars.  The eastern most of the four is set a little further off from the other three.  This fourth star is the bright 5th magnitude star in the middle of Kemble’s Cascade.    

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

There are loads of interesting objects like Kemble’s Cascade scattered throughout the sky.  Backyard astronomy is not always just about finding distant galaxies or scanning the skies trying to complete deep sky catalogs.  Sometimes a keen eye and an imagination will allow an observer to see other chance alignments of stars like Kemble’s Cascade.  Reading monthly astronomy magazines and searching out observing forums is a great way to learn about many things that will not be included in the official deep sky catalogs. 

The Object for the week of April 14 is the spiral galaxy NGC 2403.  This galaxy lies about 12 million light years away and shines with an apparent magnitude of 8.4.  At this magnitude NGC 2403 is visible in binoculars but it will be considerately more difficult to see than a star with the same magnitude.  Stars have all their light concentrated into a singular point in the sky.  Whereas galaxies and other deep sky objects have more surface area so their surface brightness appears dimmer.  This is why when we see them they are frequently described as faint and fuzzy objects. 

To find NGC 2403 start by locating the star Muscida.  This star represents the nose of Ursa Major.  From here start scanning about 12 degrees to the east of this at a slight upward angle.  About two binocular fields to the east you should be able to find the dim patch of light that is NGC 2403.  Use the maps linked below to help you find this neighboring galaxy.

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

http://www.iau.org/public/themes/constellations/#uma

The object for the week of April 21 is another spiral galaxy named IC 342.  This galaxy lies approximately 10 million light years away.  It shines with an apparent magnitude of 8.4 but as we discussed last week it will appear dimmer then a star with the same apparent magnitude.  It is a member of the IC 342/Maffei group of galaxies which is one of the closest groups to the Local Group of galaxies our Milky Way belongs to.   

To find IC 342 start by finding the two brightest stars in Camelopardalis, Beta and Alpha Cam.  Follow them north to the next brightest star Gamma Cam.  About two degrees southeast of this star is where you will find IC 342.  This galaxy is bright enough to be seen in binoculars but it will be difficult to find.  Small telescopes will also have trouble as the galaxy’s core is bright but the rest has a low surface brightness.  Follow the map linked below and you should be able to spot this galaxy.  Remember viewing conditions are important so try when the moon is not up and when humidity is low. 

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

Lyrid Meteor Shower 

The annual Lyrid meteors shower is once again upon us.  Every year around April 22nd this meteor shower becomes active as the Earth passes through the debris left by comet C/1861 G1 Thatcher.  This is a long period comet that takes approximately 415 years to orbit the Sun.  The last time this comet came close to the Earth was in 1861. 

The sand to baseball sized fragments shed by this comet as it passes by the Sun slam into our atmosphere traveling at 27.8 miles per hour.  When they hit our atmosphere they vaporize and excite the atmospheric gases around them.  This is what causes the bright streak of light we see as meteors. 

The Lyrids do not favor us this year so we can likely only hope for rates around 5 to 10 per hour.  For the best chance to see the Lyrids go outside after midnight on the 22nd and look east.  For more detailed information visit

http://amsmeteors.org/2014/04/viewing-the-2014-lyrid-meteor-shower/

Our next Star Party will be held on Friday, May 2, 2014, from dusk until 10 p.m.

Weather permitting, the St. Louis Astronomical Society and the ScienceCenter 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 May 2, 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

Join us for the Minority Scientists Showcase for the chance to interact one on one with scientists, engineers and other science related professionals. Enjoy this unique career awareness opportunity as scientists share their insights with visitors as well as demonstrate their work.

This is a FREE event.

Location: Main Building