Week of April 8, 2013

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

Information updated weekly or as needed.

Join us for our next star party, Friday, May 3, 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 6:35 a.m. on Monday, April 8 and sunset is at 7:31 p.m. providing us with nearly 13 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 9:05 p.m. this week.  Solar transit or local noon occurs around 1:04 this week.

Moonrise for Monday, April 8 is at 5:24 a.m. and moonset is at 6:07 p.m.  On Monday, April 1 the Moon will be exhibiting a waning crescent phase with roughly 3% of the lunar disk illuminated.  New moon occurs on Wednesday, April 10.  

International Space Station (ISS) Observing

Visible passes of ISS over St. Louis for the next two weeks starting the week of Monday, April 8 are all evening passes.  For this two week period the best passes occur the evenings of April 8 and 10.  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, April 8.

Date

 

Mag

Starts

Max. Altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

08 Apr

-3.4

20:24:50

10

SW

20:28:07

81

SE

20:31:24

10

NE

08 Apr

-0.4

22:02:51

10

WNW

22:04:52

17

NNW

22:04:52

17

NNW

09 Apr

-1.0

21:11:47

10

W

21:14:32

24

NNW

21:17:16

10

NNE

10 Apr

-1.8

20:20:56

10

WSW

20:24:01

37

NNW

20:27:07

10

NE

10 Apr

-0.1

20:00:19

10

NNW

22:01:22

11

NNW

22:02:15

10

N

11 Apr

-0.4

21:08:48

10

NW

21:10:40

14

NNW

21:12:32

10

NNE

12 Apr

-0.7

20:17:32

10

WNW

20:20:00

19

NNW

20:22:29

10

NNE

14 Apr

-0.4

20:14:36

10

NW

20:16:03

12

NNW

20:17:30

10

N

16 Apr

-0.4

21:48:58

10

N

21:49:58

11

NNE

21:50:15

11

NNE

17 Apr

 0.0

22:33:54

10

NNW

22:34:22

13

NNW

22:34:22

13

NNW

18 Apr

-0.9

21:43:38

10

NNW

21:45:43

17

NNE

21:45:43

17

NNE

19 Apr

-0.7

20:53:27

10

N

20:54:58

13

NNE

20:56:29

10

NE

19 Apr

-0.3

22:28:58

10

NW

22:29:49

16

NW

22:29:49

16

NW

20 Apr

-1.8

21:38:31

10

NNW

21:41:09

29

NNE

21:41:09

29

NNE

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

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

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

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

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

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

The Planets Visible Without A Telescope

Jupiter

The planet Jupiter will be visible shortly after sunset and sets around 11:55 p.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 to the right of 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 9:06 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...

PANSTARRS Update Monday, April 1, 2013

C/2011 L4 PANSTARRS has been climbing higher in the sky and now has an azimuth of roughly 290 degrees and an altitude of 25 degrees.  It has also begun to fade and is now a 3rd magnitude object.  Start looking in the western skies about 30 minutes after sunset.

PANSTARRS Update Monday, April 8, 2013

C/2011 L4 PANSTARRS is still visible in the early evening skies about 30 minutes after sunset.  Looking to the northwest during dusk the comet is about 12 degrees above the horizon.  For those willing to get up before sunrise, the comet is now higher above the horizon at dawn than it is during dusk.  Around 6:00 a.m. look to the northeast about 20 degrees above the horizon.   Recent estimates for the comets brightness have it a 4th magnitude. 

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 our constellation is Cancer the Crab.  Cancer is one of the 12 zodiacal constellations meaning that Sun, Moon and planets can be found in Caner from time to time.  It is located in the spring seasonal sky between the constellations of Gemini and Leo.  Cancer is significantly fainter then its neighbors and may be difficult to spot in light polluted conditions.   To locate Cancer either find Gemini to the upper left of Orion or Leo just below the Big Dipper’s bowl.  Cancer is west of Leo and east of Gemini.  The brightest stars in Caner form a faint upside down Y-shape.  The brightest stars are Acubens, Altarf, Asellus Borealis, Asellus Australis, ζ Cnc, ι Cnc and 55 Cnc.

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

In Greek mythology, Cancer was the giant crab that nipped at the feet of Hercules as he battled Hydra.  In ancient Egypt, Cancer was seen as the lowly scarab which was the representation of the dawn Sun-God Khephri.  It was also a symbol of fertility.

The object for the week of April 1 is Cancer’s brightest and most well known deep sky object known as M44.  Also known as the Beehive cluster or the Praesepe Cluster, M44 is an open cluster containing 350 stars shining with a combined magnitude of 3.7.  At this magnitude, M44 is visible to the unaided eye as a faint patch of nebulous light using averted vision.  Through binoculars you can easily count over 40 stars and with a large telescope roughly 200 can be seen.  The stars in this cluster are approximately 730 million years old and are 577 light years away.   

To find M44 look for the star Asellus Australlis at the branch of the upside down Y-shape described above.  From that star look approximately two degrees to the north and west and you will find M44.

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

http://messier.seds.org/m/m044.html

The object for the week of April 8 is the open star cluster M67.  Discovered in the late 1700’s, this cluster stands as one of the oldest open clusters in the Milky Way.  Previous open clusters discussed in the Night Sky Update have been hundreds of million years old whereas M67 has been estimated to be 3.2 to 4 billion years old.  Open clusters normally do not last this long due to gravitational encounters that strip members from the cluster as it moves through the Milky Way.  M67 is also relatively close at a distance of 2,700 light years making it an ideal target to study the evolution of stars.  Being so close to us, our view of M67 is mostly unobstructed by the clouds of soot and dust that permeate the Milky Way.  So the light we see from these stars has gone through very little change or filtering as it travels to us.  In M67 there are nearly 200 white dwarfs, main sequence stars of all types and a number of aging giant stars.  With this spread scientists have clear views of nearly all types of stars in various evolutionary stages. 

To find M67 look for the upside down Y-shape of Cancer.  The bottom left star of the Y-shape is Acubens.  From there look about 1.5 degrees to the west and you will find M67.  With an apparent magnitude of 6.1, M67 is an easy target for binoculars.  City lights will make things much more difficult but it should be visible.  Through a telescope stars in M67 can be resolved with a faint patch of nebulous light in the background.    

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

http://messier.seds.org/m/m067.html

NASA Mission of the Month

Each month we will be celebrating a NASA mission of the month.  This month’s mission is the Hubble Space Telescope.  This telescope is named after the famous astronomer Edwin Hubble who showed us that the universe was huge and was expanding at exceeding rates.  This discovery revolutionized astronomy.  Much like the astronomer, the telescope continues to push our understanding of the universe and allows astronomers to see some of the most distant objects ever observed.  The Hubble Space Telescope has been in space now for over 20 years and has made over 1 million observations.  It continues to shed light on the universe and its origin.  To learn more about the Hubble Space Telescope visit

http://hubblesite.org/

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, May 3, 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 May 3, join us indoors in our Planetarium Theater for “The Sky Tonight”.  Showtime is at 8 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 8 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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