Week of November 25, 2013

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, November 25.  All times are given as local St. Louis time (Central Standard 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, December 6, 2013 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 6:54 a.m. on Monday, November 25 and sunset is at 4:4s p.m. providing us with only 10 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 6:15 p.m. this week.  For those with a sun dial, solar transit or local noon occurs around 11:48 a.m. this week. 

Moonrise for Monday, November 25 occurs three minutes after midnight; technically this places moonrise in the following morning hours. Moonset will occur at 12:13 p.m. during daylight hours.  The Moon starts this week at first quarter phase and ends with a waning crescent phase.

International Space Station (ISS) Observing

The next visible passes of ISS over St. Louis are all morning passes.  All passes this week are good but the best occur between November 27 and December 1.  See the table below for information regarding this pass.

If you do not want to wake up early to catch ISS you might try your hand at finding the Hubble Space Telescope (HST).  This week there are some better than average passes of HST.  You will need a clear southern horizon and a pair of binocular might help.  Follow this link for more information.  http://heavens-above.com/PassSummary.aspx?satid=20580&lat=38.62722&lng=-90.19778&loc=Saint+Louis&alt=135&tz=CST&cul=en-GB  

Catch ISS flying over St. Louis in the morning hours starting Monday, November 25. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

26 Nov

-0.8

04:55:55

15

NNE

04:55:55

15

NNE

04:57:49

10

ENE

27 Nov

-2.4

05:42:01

20

NNW

05:43:58

44

NE

05:47:10

10

ESE

28 Nov

-1.5

04:55:16

27

NE

04:55:16

27

NE

04:57:51

10

E

29 Nov

-3.2

05:41:26

31

WNW

05:42:48

63

SW

05:46:05

10

SE

30 Nov

-2.1

04:54:47

42

ESE

04:54:47

42

ESE

04:57:09

10

ESE

01 Dec

-1.7

05:41:05

20

SW

05:41:20

20

SW

05:43:52

10

S

02 Dec

-0.9

04:54:32

18

SSE

04:54:32

18

SSE

04:55:33

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

Mercury

Mercury has once again risen out of the glare of the Sun.  It rises at 5:25 a.m. and should be visible by 5:40 a.m. for those with clear eastern horizons.  If you can spot Mercury grab a pair of binoculars and you can find Saturn and the double star Zubenelgenubi.  Maximum eastern elongation occurred on November 17th so Mercury is already on it way back around the Sun.  Look for Mercury while you can as twilight will rob us of this elusive planet soon.

Venus

The brightest planet in the sky is well into another evening apparition becoming visible about 20 minutes after sunset.  Venus will be low to the horizon and any trees or buildings southwest of you may obscure it from view.  Venus is currently seen in the constellation Sagittarius and will set by 7:30 p.m.  If you have binoculars at home you should notice that Venus in a crescent phase.  Due to Venus being closer to the Sun it is always in a phase similar to those we see the Moon exhibit.  The difference is Venus is always closer to the Sun so we never see a full Venus.  As Venus approaches its inferior conjunction in January next year, Venus will exhibit a thinner and thinner crescent shape.    

Mars

Mars is now in the constellation Virgo and will rise around 1:07 a.m. this week.  For those awake around 2:30 a.m. look to the east and you will see a reddish-orange object just above the horizon.  Mars will be seen earlier each week as we start to catch up with it in our orbit.  Mars will be close to us again in 2014 reaching opposition on April 8, 2014.  Fans of Mars rejoice it is back and on its way to another close approach.

Jupiter

The largest planet in our solar system has returned to our evening skies.  This week it will rise around 7:50 p.m. becoming visible roughly 30 minutes later.  Just above and to the east of Jupiter you will see the 1st magnitude stars Castor and Pollux.  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 will be at opposition on December 2, 2013.  After this date Jupiter will be rising as the Sun is setting.

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 November is Aquarius the Water Bearer.  The Greek legend of Aquarius involves a young price of Troy named Ganymede.  He was chosen by Zeus to be his water bearer and was brought to Olympus.  During his time as Zeus’s water bearer he saw that humanity was in need of water so he pleaded with Zeus to give them rains.  For his effort Ganymede was made god of rain and was placed into the sky as Aquarius the Water Bearer.  As we have discussed in previous months, not every culture believed the same thing as the next.  For instance the Babylonians saw Aquarius as an overflowing urn of water and the Egyptians saw him as the God of the Nile Hapi.  With the many interpretations one thing usually remained the same, that part of the sky was always associated with water.

Aquarius is also one of the famed constellations of the zodiac.  In astronomy these are the constellations created by ancient astronomers to track the movement of the planets.  As they watched the sky, ancient astronomers notice some strange stars that moved separately from the rest of the stars.  Not knowing what they were they gave them the name asters planetai which means wandering star.  As they followed them they always seemed to wander amongst a set path.  To keep track of these wandering stars they created 11 constellations with a 12th added when the Julian calendar was invented.  The wandering stars turned out to be planets and to this day you will find the planets wandering amongst the zodiac constellations.  Those with binoculars and telescopes can find the planet Neptune just east of the border between Aquarius and Capricornus.  Read below for more information.

To find Aquarius look to the south once it is dark enough to see stars.  Looking to the south you will see a large smile shape of stars.  This is the constellation Capricornus.  Once you can find this look above and to the east of the smile and you will see Aquarius.  Unfortunately Aquarius is not a bright constellation and will take some time to see while your eyes begin to adjust to the growing darkness.  One pattern of stars I look for is near the bottom of Aquarius and it looks like the planetarium building.  This represents the jar that Aquarius is pouring water in. If you are having troubles locating this shape use the map linked below to help you find these and the rest of the stars in Aquarius.

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

The first object we will talk about in Aquarius is the planetary nebula NGC 7293 also known as the Helix nebula.  This cloud of dust and gas is the blown off outer layers of a star similar to the Sun that has started the last phase of its stellar existence.  When looking at this deep sky object the glowing gases you see are being excited by UV radiation emitted by the dense hot core of the star that has been exposed.  This stage in the stars life will last only 10,000 years before the core cools off as nuclear fusion shuts down.  This will happen to the Sun in roughly five billion years.

To find the Helix nebula first locate the star Fomalhaut in the constellation Piscis Austrinus.  This star and constellation lie just south of Aquarius.  Fomalhaut will be easy to spot as it is the one lone bright star in the southern skies.  From Fomalhaut look north until to you come across another semi bright star named Skat.  From Skat start looking six degrees in the direction the 4 o’clock would be on a clock face.  As you do this you will come across two 5th magnitude stars 66 and 68 Aquarii and then a triangle shape of stars.  The Helix Nebula will be roughly one degree to the right of this triangle shape.

The Helix nebula is listed as a 6.5 magnitude object which means you should be able to see it through a pair of 7x50 or 10x50 binoculars.  The problem you will experience is that even though it is listed as 6.5 magnitude it is a large object meaning all that brightness is spread over a large area.  Due to this the nebula has a low surface brightness and will require ideal viewing conditions to be seen in binoculars.  Small telescopes should have no problem seeing this nebula. 

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

The Object for the week of November 11 is the globular star cluster M2.  This star cluster lies at a distance of 37,500 light years away and is a member of the Milky Way’s out halo.  It is one of the largest of the Milky Way’s globular cluster with a diameter of 175 light years.  Its age is estimated to be 13 billion years which makes this one of the oldest clusters in the Milky Way.  It will appear as a dense slightly elongated cluster that is easily visible in binoculars and small telescopes.  Individual stars can be resolved in larger telescopes.

To find M2 look for the smile shape of the constellation Capricornus in the southern skies.  From the left half of the smile look north until you see a bright star, this is Beta Aquarii.  Once you locate this star look about 5 degrees to the north.  In binoculars you will see a fuzzy object that is clearly not a star; this is the star cluster M2.  Use the links below to help find this large globular cluster and learn more about it.

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

http://messier.seds.org/m/m002.html

The Object of the week of November 18 is the planet Neptune.  Named after the Roman god of the sea this was the eighth planet discovered in our solar system.  It orbits the Sun at an average distance of 30.1 AU.  At this distance 164.79 Earth years will occur before Neptune completes one orbit around the Sun.  Since its discovery only one Neptunian orbit has occurred.  The planet was first observed on September 23, 1846 by astronomer Johann Galle who was using coordinates that were calculated by French mathematician Urbain le Verrier. 

Neptune is one of the four gaseous planets in the solar system.  Like Jupiter and Saturn it is mostly comprised of hydrogen and helium.  Neptune also contains large amounts of water, ammonia and methane.  These volatiles are called ices in planetary sciences so Neptune and Uranus are frequently called ice giants.  The interior portions that contain these ices are not frozen but rather are super cooled fluids.  A good analogy would be a slushy you get from your local convenient store.  The methane in the atmosphere of Neptune scatters the red wavelengths of light and reflects the blue.  This is what gives both Neptune and Uranus their characteristic bluish colors.    

Neptune and Uranus pose a problem for models of how the solar system formed.  Matter density was not high enough in the outer solar system to account for the formation of large planets like Neptune and Uranus.  There are a number of ideas that have been proposed to explain this but the best so far has been the Nice Model.  According to this model the planets Neptune and Uranus formed much closer to Saturn and Jupiter with Neptune being the closer of the two.  The Nice model suggests that due to gravitational interactions with Saturn and Jupiter both Neptune and Uranus were ejected out further to where we see them today.  This model also helps explain the Late Heavy Bombardment Period and Neptune’s effect on the Kuiper Belt.

Like the other gas planets Neptune has a number of icy moons and a system of rings.  NASA lists Neptune’s moon count to be 14.  Neptune’s ring system was first detected in the 1980’s when star occultations exhibited an extra blink before and after the star was behind Neptune.  The first photographic evidence was received when Voyager 2 was approaching Neptune in 1989. 

Finding Neptune will be a little tricky as it is currently 7.9 magnitude.  At this brightness it is still within reach of 50mm binoculars but it will take some patience and a good star chart with at least 7th magnitude stars.  This week the Moon also poses a slight problem as it starts the week off at full moon and spends the rest of the week in a gibbous phase.  To locate Neptune first start by finding the smile shape of the constellation Capricornus.  Using binoculars start with the east side of the smile and follow the corner of the mouth in the direction it points.  Doing this you will find a 4th magnitude star named Iota Aquarii about 5.5 degrees from the end of the smile.  From Iota Aquarii keep scanning in the same direction and you will find two 5th magnitude stars that form a triangle with Iota Aquarii.  If you have a detailed enough star chart or planetarium software these stars are called 42 and 38 Aquarii.  The southern star of this pair is 42 Aquarii and will be the closer of the two stars to Neptune.  Below you will find articles and two maps that will help you learn more about and find Neptune through the rest of the year.

http://solarsystem.nasa.gov/planets/profile.cfm?Object=Neptune

http://www.skyandtelescope.com/observing/highlights/Uranus-and-Neptune-in-2013-190064991.html

http://media.skyandtelescope.com/documents/Uranus-Neptune-2013.pdf

http://freestarcharts.com/images/Articles/Month/Nov2013/Planets/Neptune/Neptune_Nov2013_Finder_Chart.pdf

Our final object for November is Messier object 73 (M73).  This grouping of four stars is one of the objects on the Messier and New General Catalog (NGC) list of deep sky objects.  These catalogues are collections of star clusters, nebulas and galaxies.  Even the great observers get things wrong as was the case with Messier 73.  Charles Messier the namesake for the Messier Catalog originally discovered M73 and described it as a loose star cluster with an associated nebulosity surrounding it.  John Herschel, son of William Herschel, revisited M73 and could not find the nebulosity that Messier reported.  Regardless he went ahead and listed it as NGC 6994 on his New General Catalog of star clusters, nebulas and galaxies.  Debate remained until recently when it was confirmed that the four stars of M73 were not part of a cluster as the stars in this grouping have different distances.  Furthermore the proper motion of these stars is not the same.  So in reality M73 is not a star cluster but rather a four star asterism. 

M73 is only a 9th magnitude object so for those fighting light pollution you will likely need a small telescope to see it.  If you have a pair of 50mm binoculars it will hover on the edge of visibility but a telescope will be needed to separate it into its four separate component stars.

To locate M73 first find the stars Theta (θ) Capricornus and Epsilon (ε) Aquarii.  Scanning the skies about halfway between these stars will first reveal M73 and the globular star cluster M72.  The key to finding these two objects will be to use the 6th magnitude stars that extend north of Theta Capricornus.  The map that will be linked below will contain stars down to 7th magnitude and will be needed to identify both M73 and M72.  Another additional object you can look for will be NGC 7009 or the Saturn Nebula.  This is a planetary nebula that is bright and easy to spot in small telescopes but will need larger telescopes to distinguish the shape that gives the nebula its name.  NGC 7009 is a bit more than two degrees to the northeast of M73.  In St. Louis all three of these objects will require a small telescope to spot. 

http://freestarcharts.com/images/Articles/Messier/M30_M72_M73_Finder_Chart.pdf

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

2013 Year of the Comet Part II

Earlier in the year we talked about 2013 as being year of the comet.  In the spring we had Comet PANSTARRS and for the end of the year we mentioned Comet ISON that was first predicated to become visible to the naked eye and had the chance to become as bright as the full moon.  Well, so far the year of the comet has not panned out as people were hoping for. 

Comet PANSTARRS was supposed to become visible to the naked eye but for most it remained just beyond naked eye visibility.  It was still quite beautiful through binoculars and telescopes but it did not break the naked eye threshold for most observers. 

Now that we are nearing Comet ISON’s perihelion on November 28 we have learned a lot more about this comet and the new information is not as promising as people were hoping.  First of all anytime you hear a predication as fantastic as a comet becoming brighter than the full moon, assume it is too good to be true.  Predictions like that tend to be misleading and generate false hope.  Comets are also very fickle.  Until they get closer to the Sun it is hard to accurately predict how they will behave; especially for comets like ISON that have never been this close to the Sun.  Comets are unpredictable, unstable and will often break up before or during their perihelion.   With that said, Comet ISON could still be a spectacular comet.  It is not brightening like people hoped but that doesn’t mean it will be bad.  In fact even if ISON breaks up during its perihelion it could still put on an amazing display if enough of the comet survives. 

Looking back on 2011 we can find another comet named Comet Lovejoy that like ISON was a sun grazer.  Defying expectations, Comet Lovejoy passing a mere 87,000 miles from the surface of the Sun reemerged on the other side surviving its close approach.  Having survived its perihelion, Comet Lovejoy went on to display an amazing tail that spanned 20 degrees of sky.  Early observations of this comet shortly after its perihelion showed a bar shaped nucleus that experienced an outburst of dust.  This was likely related to a cataclysmic fragmentation of the comet that led to its destruction.  A few days after the outburst, no nucleus could be detected even though the tails of the comet remained visible.  This could be the future of Comet ISON.  Due to Comet ISON being new to the inner solar system it will likely have high amounts of volatiles that as heated up by the Sun could trigger a similar fragmentation event that Lovejoy experienced.  The hope is that if fragmentation occurs it does not happen before its perihelion. 

So what do we know about Comet ISON.  We know that on November 28, 2013 the comet will pass only 730,000 miles from the surface of the Sun.  We know that it will be passing through the Sun’s atmosphere meaning it will experience temperatures that can exceed millions of degrees.   With temperatures that high the volatiles, metals and other material in the comet will be vaporized.  The question remains how much of the comet will survive this brutal environment?  We know that the comet comes from the Oort cloud and that this will likely be our one and only look at this comet.  Current estimates have Comet ISON as a 10th to 11th magnitude object.  In November there is some speculation that Comet ISON will brighten enough to be seen through binoculars but that remains to be seen. 

What we don’t know is how large the comet is.  Based on April observations done by the Hubble Space Telescope, scientists have estimated the comet is no larger than 3 miles across.  We do not know how bright it will become.  There are some suggesting it will still brighten to naked eye visibility while some think at best it will be a 4th magnitude object that most will need binoculars to see.  So unfortunately it is a waiting game to see how ISON will behave.  All we can do is cross our fingers and hope for the best.

Those with telescopes will have an additional treat as they track Comet ISON during its slide towards the Sun.  In early November Comet ISON will not be alone in the sky.  Comet Encke, a new Comet Lovejoy and Comet Linear X1 will be in the same eastern skies.  On November 9, 2013 these four comets and the planets Mars and Jupiter will all be together.  The Planets will be visible to the unaided eye but the comets will require a telescope.  Comet Encke and ISON will be around 6th magnitude, Comet 2013 R/1 Lovejoy will only be 9th magnitude and Comet Linear X1 is exploding which caused a 100 fold brightening bringing it up to roughly 8.5 magnitude.  In November all of these comets will be observable in the east but all will likely be difficult to see. 

Year of the comet still seems a worthy moniker for 2013 but we will have to see if ISON lives up to the hype.  There are some great astronomy websites available to those interested in following updates related to any of the comets listed in this article.  You will find links to some of them below.  You can also use various desktop planetariums to help map and locate the comets.  Some are better than others and some cost money and some are free.  To find information about these go online and search for desktop planetariums or look up your local astronomy club and they may have information about these on their websites.  The tool I would recommend to all is a good star atlas.  These are maps of the sky that are broken down into sections.  Most label a variety of deep sky objects, double/multiple stars and variable stars so they will be useful beyond observing these comets.  Finding a star atlas that has a limiting magnitude of 8 or lower will be the best choice.  These types of maps will allow you to better scan the fainter stars in the vicinity of the comet aiding in your observations.  With any luck we will have three comets and one great comet at the end of the year. 

Articles with Comet ISON Updates

http://www.skyandtelescope.com/observing/objects/comets/Comet-ISON-Updates-193909261.html

http://astronomy.com/magazine/events/comet-ison

http://www.spaceweather.com/

http://observing.skyhound.com/ISON.html

http://science.nasa.gov/science-news/science-at-nasa/2013/19apr_isonids/

General Comet Information

http://cometchasing.skyhound.com/

http://cometography.com/

http://www.nasa.gov/content/goddard/timeline-of-comet-ison-s-dangerous-journey/#.Um6UWFOE6So

http://knowyournightsky.blogspot.com/p/comet-ison.html

Star Charts Showing Comet Locations in the Sky

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

http://freestarcharts.com/images/Articles/Month/Nov2013/Comet_Lovejoy/C2013_R1_Lovejoy_Nov_3_Finder_Chart.pdf

http://freestarcharts.com/images/Articles/Month/Oct2013/Comet_LINEAR/C2012_X1_LINEAR_2013_Finder_Chart.pdf

Comet Update 11/28/2013:

Comet Lovejoy (C/2013 R1): This comet remains a great comet through a pair of binoculars and can now be found in Canis Venatici under the Big Dipper’s handle.  By the end of the week Comet Lovejoy will enter the constellation Bootes.  Use the finder chart above to locate this comet.

Comet ISON (C.2012 S1): Comet ISON is now lost in the glare of twilight just before the Sun rises.  November 28th Comet ISON will reach perihelion passing a mere 730,000 miles from the Sun.  The core of the comet will be heated to nearly 5,000 degrees Fahrenheit.  If it or enough of it survives we may be treated to a spectacular comet.  We will just have to wait and see.  For now we will have to rely on views from solar telescopes to keep track of the comet.  Tune in to these various solar telescope websites to track ISON as it plunges towards the Sun.

http://spaceweather.com/

http://sdo.gsfc.nasa.gov/

http://sohowww.nascom.nasa.gov/

http://stereo.gsfc.nasa.gov/

http://events.slooh.com/     

Comet 2/P Encke: This comet like ISON is now lost in the glare of twilight.  Use the same solar telescope links above to track this comet.

Comet Linear X1: This comet is still hanging at near 8th magnitude so it should only get easier to see as the Moon continues to move towards new moon.  If you have a small telescope or large binoculars this comet should be visible in moderate light pollution.  Use the link above to find daily locations for this comet.

NASA Mission of the Month

Each month we will be celebrating a NASA mission of the month.  This month’s mission is the International Space Station.  The first segment was launched in 1998 and the last segment of ISS to be installed was Leonardo installed in 2011.  In essence ISS is complete but there are future modules scheduled to be installed later down the road.  ISS is an international effort made by five space agencies (NASA, RSA, ESA, CSA and JAXA) to build the most technologically advanced space craft ever built.  It is a laboratory in space that allows scientists around the world to study the effects of long duration space flight on humans and technology, physics, chemistry, biology, etc.  Studies done aboard ISS not only further advance humanity’s ability to explore space but it also directly benefits our lives on Earth.  To learn more about ISS, its work and the developments that make all our lives better visit

http://www.nasa.gov/mission_pages/station/main/index.html#.UnajtyeFeSp

http://spinoff.nasa.gov/

50th Anniversary of the James S. McDonnell Planetarium

2013 marks the 50th anniversary of the James S. McDonnell Planetarium.  There are a number of events planned for the year that will celebrate the 50th anniversary.

Our next Star Party will be held on Friday, November 1, 2013, 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 November 1, join us indoors in our planetarium theater for “The Sky Tonight”.  Showtime is at 7 p.m.  As there is a 7 p.m. star show there will be only one Laserium show on all First Fridays.  This show begins at 8:30 p.m.  Information for laser shows can be found at http://www.slsc.org/laserium

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

http://www.slsc.org/laserium

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