Week of March 25, 2013

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

Information updated weekly or as needed.

Join us for our next star party, Friday, April 5, 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 6:56 a.m. on Monday, March 25 and sunset is at 7:18 p.m. providing us with over 12 hours of daylight.  Even after sunset, the light from the Sun will still illuminate our sky for roughly 1.5 hours.  This period of time is called twilight, which ends around 8:50 p.m. this week. 

Moonrise for Monday, March 25 is at 5:50 p.m. and moonset is at 6:11 a.m. on the following day.  On Monday, March 18 the Moon will be exhibiting a waning gibbous phase with roughly 96% of the lunar disk illuminated.  Full moon occurs on Wednesday, March 27 and is known as the Full Worm Moon.    

International Space Station (ISS) Observing

Visible passes of ISS over St. Louis for the next two weeks starting the week of Monday, March 25 are mostly morning passes with a few evening passes at the end of next week.  For this two week period the best passes occur on the mornings of April 2, 3, 4 and 5.  For more detailed information regarding these and other passes click the red links in the table.

Catch ISS flying over St. Louis in the morning hours during the week of Monday, March 25.

Date

 

Mag

Starts

Max. Altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

30 Mar

-0.3

04:53:22

10

N

04:54:25

11

NNE

04:55:27

10

NNE

31 Mar

-1.1

05:38:22

10

NNW

05:41:06

24

NNE

05:43:50

10

E

01 Apr

-0.6

04:48:42

12

NNW

04:50:24

17

NNE

04:52:37

10

ENE

02 Apr

 0.1

04:00:29

12

NE

04:00:29

12

NE

04:01:09

10

NE

02 Apr

-2.6

05:33:35

10

NW

05:36:47

54

NE

05:39:59

10

ESE

03 Apr

-1.6

04:45:17

26

N

04:46:09

31

NNE

04:49:09

10

E

04 Apr

 0.0

03:57:33

12

ENE

03:57:33

12

ENE

03:57:58

10

ENE

04 Apr

-3.2

05:30:22

22

WNW

05:32:13

52

SW

05:35:23

10

SE

05 Apr

-1.9

04:42:59

33

ESE

04:42:59

33

ESE

04:44:55

10

SE

05 Apr

-0.7

21:18:21

10

SW

21:18:41

12

SSW

21:18:41

12

SSW

06 Apr

-1.3

05:28:49

14

SSW

05:28:49

14

SSW

05:29:43

10

S

06 Apr

-2.3

20:28:14

10

SSW

20:31:02

26

SE

20:31:55

23

ESE

06 Apr

-0.1

22:04:35

10

W

22:04:47

11

W

22:04:47

11

W

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

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

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

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

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

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

The Planets Visible Without A Telescope

Jupiter

The planet Jupiter will be visible shortly after sunset and sets around 12:30 a.m.  Grab a pair of binoculars and see how many of the Galilean moons you can see.  Depending on when you look you should be able to see all four; Io, Europa, Ganymede and Callisto.  As you watch them sketch their locations relative to Jupiter and you will be following in the footsteps of Galileo.  While looking at Jupiter see if you can spot the stars Kappa and Upsilon Tauri just above the planet.  Both of these stars are multiple star systems with Kappa being two stars and Upsilon being three.  Both systems are members of the V-shaped star cluster called the Hyades just below Jupiter.    

Saturn

Look for the ringed planet shortly after it rises around 10:00 p.m. this week.  Currently Saturn is found in the constellation Libra just to the west of the bright stars Zubeneschamali and Zubenalgenubi.  Opposition for Saturn occurs on April 28, 2013.  As we approach this date Saturn will continue to brighten and be seen early each night.  Once opposition occurs Saturn will be visible shortly after sunset.

2013 Year of the Comets?

In 2013 we may be treated to two spectacular comets.  These comets are called C/2011 L4 PANSTARRS and C/2012 S1 ISON.  Comets are named after whom or what discovers them and in both cases they were discovered by sky surveys.  The first comet we will see this year is C/2011 L4 PANSTARRS.  This comet is a long period comet with a near parabolic orbit that will likely not return to our skies for thousands to millions of years.  It reaches it closest point to the Earth (1.1 AU) on March 5, 2013 and its closest point to the Sun (0.3 AU, perihelion) March 10, 2013.  It will be visible throughout March and will be at its brightest on March 8-12.  Its greatest northern declination occurs on May 28, 2013 when it reaches a declination of +85.2 degrees.  Original predictions for peak brightness were -1 magnitude but have been downgraded 2 or 3 magnitude.  Even being a bit fainter then originally predicted, it should still be bright enough to be seen to the unaided eye.  

To find C/2011 L4 PANSTARRS, look low to the west starting 30 minutes after sunset on March 8.  Unfortunately it will be below 10 degrees up for the days it will be at its brightest.  If you have any trees or buildings west of your viewing location you will likely have issues finding the comet.  If this is the case look for a large parking lot near by that is open to the western skies.  Such places would be grocery stores, shopping malls, parks or anywhere with a large lot.  Be aware though that not all parks are open after sunset and some businesses may not want you on their lots.  If you plan to try and spot the comet with a telescope or plan to bring friends be sure to call ahead and check to make sure it is ok with the powers that be.  Links below have use articles or images pertaining to C/2011 L4 PANSTARRS.

http://www.skyandtelescope.com/observing/highlights/194257261.html

http://www.skyandtelescope.com/observing/highlights/185665152.html

http://spaceweather.com/

PANSTARRS Update Monday, March 18, 2013

So far Comet C/2011 L4 PANSTARRS has remained elusive to the unaided eye.  It is however easy to see through binoculars provided you know where to look.  Your best bet will be to go outside around 7:30 p.m. and locate west.  Start scanning the sky about 10 degrees north of west and 13 degrees above the horizon.  By 8:00 p.m. it will be roughly 7 degrees above the horizon.  You are looking for a bright coma with a distinct but short tail. 

http://www.skyandtelescope.com/observing/highlights/Spot-Comet-PanSTARRS-in-Twilight-196688441.html

PANSTARRS Update Monday, March 25, 2013

C/2011 L4 PANSTARRS remains a binocular object for northern hemisphere observers.  Recently it has been estimated to be at 1.8 magnitude but due to the twilight glare it remains undetectable to most naked-eye observers.  To find the comet you now need to scan the skies at an azimuth of about 283 degrees and about 12 degrees above the horizon at the end of civil twilight. 

http://www.skyandtelescope.com/observing/highlights/Spot-Comet-PanSTARRS-in-Twilight-196688441.html

C/2012 S1 ISON

The second comet for this year comes much later in late November and December and is called C/2012 S1 ISON.  This comet is predicted to get as bright as the full moon if it survives its perihelion.  It is hard to not get our hopes up for predictions like this but comets are fickle things and do not always behave as predicted.  Also of interest is this comet might produce a meteor shower sometime in early 2014.  If this is the case it should be a spectacular shower that could even turn into a meteor storm.  Stay tuned for more information on this comet as we get closer to the end of the year.       

Constellation of the Month

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

This month will be a little different as we will cover a few different constellations.  As we begin to transfer from the familiar winter skies to the spring sky we are beginning to look away from the galactic plane.  In doing this we are looking at parts of the sky with less dense star fields.  In other words there are simply less stars to look at.  As many of us are urban astronomers this makes large parts of the sky appear to be nearly void of stars.  Because of this many constellation go unnoticed due to the lack of a recognizable pattern of stars.  This month we will cover some of the rarely heard of constellations as many of them have great things to offer just like those that are more familiar to us.

The first constellation we will explore is Puppis.  This constellation is better observed in the southern hemisphere but during the winter months it does rise above our southern horizon.  In fact half of the constellation is adjacent to last month’s constellation Canis Major.  Puppis along with Carina and Vela were originally part of one constellation called Argo Navis.  In Greek mythology this was the boat that Jason and the Argonauts sailed in during their quest to find the Golden Fleece.  In 1763 Nicolas de Lacaille broke Argo Navis into its three modern day constellations; Puppis (The Stern), Carina (The Keel) and Vela (The Sails).  Unfortunately there are not many bright stars in Puppis and those that are relatively bright are few and far between.  Which is odd as the galactic equator runs through parts of Puppis.    

To find Puppis, follow Orion’s belt down to Sirius like we did last month.  Below Sirius were the three stars Wesen, Aludra and Adhara.  If you look about 5 degrees to the east of these three stars you will see three stars extending in a rough line from Aludra.  These stars are named HIP37229, Asmidiske and Rho Puppis and are what you will use to find Puppis.  Puppis extends from the top of Canis Major down to roughly 5 degrees above the horizon.  Part of Puppis also hooks below Canis Major making it nearly twice as big as the great dog.

The objects we will explore in Puppis are two open star clusters named M46 and M47.  Both star clusters are bright enough for binoculars.  M46 is the dimmer of the two shinning at magnitude 6.1.  Even though it is dimmer it will be easier to find as there are more stars in the cluster and it will have a nebulous appearance.  M46 contains approximately 100 visible stars and a total of roughly 500 that are about 300 million years old.  The cluster lies at a distance of 3,200 light years meaning that light we see each night from this cluster started its journey 3,200 years ago.  In dark skies and with large telescopes there is a fine planetary nebula named NGC 2438 visible in front of the cluster.  Planetary nebulas are the remnants of a star’s outer envelope of plasma that it shed at the end of its stellar life.  This is the future of the Sun roughly 5 billion years from now.  To find M46 look about 13 degrees (a little more than a fist’s width) directly to the left of the star Sirius.  Scanning this part of the sky with binoculars will reveal a subtle patch of nebulous light; this is M46.  

Our other star cluster M47 is 4.4 magnitude but only contains 50 stars with no distinct concentration.  The cluster is roughly 1,800 light years away and the stars are approximately 300 million years old.  Some of the component stars are visible to the unaided eye but most will require binoculars to see.  To find M47 use the same method described for M46 but look one degree up and to the right of M46.  Here you will find a loose scatter stars which is M47.

http://www.iau.org/static/public/constellations/pdf/PUP.pdf

http://messier.seds.org/m/m046.html

http://messier.seds.org/m/m047.html

Week of March 11, we will stay in Puppis one more week and find another bright star cluster called M93.  This open cluster contains approximately 80 stars that shine at a combined magnitude of 6.2.  This puts the cluster well within the range of binoculars and small telescopes.  These stars are roughly 100 million years old and are approximately 3,600 light years away.  To find M93 locate Omicron 1 & 2 CMa.  These two bright stars are just above the three that make the triangle at the bottom of Canis Major.  Head straight east about 10 degrees from Omicron 1 & 2 CMa and you will find a tight group of stars in an arrowhead shape not well detached from the background stars; this is M93.  This was one of the last deep sky objects Charles Messier discovered and included in his catalog. 

http://messier.seds.org/m/m093.html

http://iau.org/static/public/constellations/pdf/PUP.pdf

The constellation for the week of March 18 is Monoceros the Unicorn.  This constellation is modern and was named in the early 1600’s by Dutch astronomer Petrus Plancius.  To find Monoceros look north of the bright star Sirius and east of the constellation Orion.  This relatively dim part of the sky has a nice knot of deep sky objects near its border with Gemini.  In the northwest corner of Monoceros there are six star clusters that are members of the Collinder catalog.  In the same vicinity there are also the famous Cone and Rosette nebulas and a number of dark nebulas for those in locations dark enough to see the glow of the Milky Way.  None of these objects will be easy pulls for city observers but all are worth looking at as you continue to scan the galactic equator.  Much like Puppis, the galactic equator runs through Monoceros.  Objects to look for are: Cr107, Cr106, Cr97, Cr111, Cr92, Cr91 and the Cone and Rose Nebulas.  Both nebulas are emission nebulas and will be identifiable by a faint background glow near the star clusters listed above. 

The constellation for the week of March 25 is Hydra.  This constellation will transition our explorations from the winter to the spring sky that will come to dominate the early evenings.  Like the spring sky most of Hydra is in an area that has an observer looking away from the concentration of the Milky Way galaxy.  Simply put the spring sky has fewer stars to look at.  Hydra is a long constellation that stretches from the west side of Monoceros and Puppis all the way over to Libra.  Hydra is always seen low to the horizon which also makes it difficult to observe as the glare from the city lights washes out most of Hydra’s stars.

In Greek mythology Hydra was the nine-headed beast that killed and ate any traveler that ventured too close to his home.  As part of his twelve labors, the hero Hercules was instructed to slay the beast.  Hydra was difficult to slay as once one head was cut off another one grew back in its place.  Once he realized this Hercules and his nephew Iolaus cauterized each neck once the head was removed.  In doing this Hercules was able to slay the beast Hydra.

Most of Hydra is far removed from the galactic equator we have been exploring through the month of March.  However, his head is positioned just east of the galactic equator and serves as a way to transition into the spring sky.  The object we will look for this week is another open star cluster known as M48.  This star cluster contains about 80 stars that shine at a combined magnitude of 5.8.  This puts this star cluster within range of binoculars and telescopes and may even be visible to the unaided eye as a small nebulous patch of light in dark skies.  The stars of M48 are approximately 300 million years old and roughly 1500 light years distant.  To find M48 look for the bright star Procyon in Canis Minor.  From there using binoculars scan the sky approximately 10 degrees to the southeast of Procyon and you should see a large detached grouping of stars in a well-defined cluster.    

http://iau.org/static/public/constellations/pdf/HYA.pdf

http://messier.seds.org/m/m048.html

NASA Mission of the Month

Each month we will be celebrating a NASA mission of the month.  This month’s mission is the Kepler Mission.  Kepler is a telescope mission designed to look for planets orbiting other stars (exoplanets).  Kepler is looking for tiny fluctuations in the light from stars which may indicate a planet has transited across the visible face of the star.  These fluctuations can be caused by other processes but with repeat observations Kepler and other observatories will be able to determine if the light fluctuation was caused by a planet or some other process.  Kepler is observing the star field between the constellations Cygnus and Lyra, looking at Sun like stars no more than 3,000 light years away.  Kepler along with other observatories have confirmed 932 exoplanets and located another 2,717 candidates.  Based on the rates of discovery, scientists believe there may be as many as 100 billion exoplanets in our galaxy alone.  Apply these numbers to the billions of other galaxies and planets become way more numerous than we ever thought.  Preliminary results are indicating the Earth-like and giants Earths are more abundant then most other planet types.  A new Earth has not been found but in time scientists likely will discover one.  To learn more about the Kepler mission and the hunt of exoplanets follow the links below.

http://kepler.nasa.gov/

http://planetquest.jpl.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.  For more information about the planetarium and the 50th anniversary, visit www.slsc.org

 

 

Our next Star Party will be held on Friday, April 5, 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 7:30 p.m.  Regardless of the weather on April 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

 

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