Week of March 24, 2014

This is the Saint Louis Science Center’s NIGHT SKY UPDATE for the week of Monday, March 24.  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 4, 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 6:58 a.m. on Monday, March 24 and sunset is at 7:17 p.m. providing us with over 12 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 8:46 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, March 24 occurs at 2:25 a.m.  Moonset will occur at 12:46 p.m.  On Monday the 3rd the Moon will be exhibiting a waning crescent phase with roughly 43% of the lunar disk illuminated.  New moon occurs on March 30.

International Space Station (ISS) Observing

The next visible passes of ISS over St. Louis are all morning passes.  The best passes are on the mornings of March 30 and 31.  Learn more about these passes and others this week in the table below.

Catch HST flying over St. Louis in the evening hours starting Monday, March 24. 

Date

Mag

Starts

Max. altitude

Ends

Time

Alt.

Az.

Time

Alt.

Az.

Time

Alt.

Az.

26 Mar

-0.5

06:19:15

10

NNW

06:21:17

15

NNE

06:23:19

10

ENE

27 Mar

-0.4

05:30:16

10

N

05:31:36

12

NNE

05:32:56

10

NE

28 Mar

-1.2

06:16:31

10

NNW

06:19:24

26

NNE

06:22:17

10

E

29 Mar

-0.7

05:27:17

10

NNW

05:29:43

19

NNE

05:32:09

10

ENE

30 Mar

-0.4

04:38:53

12

N

04:39:56

14

NNE

04:41:46

10

NE

30 Mar

-2.8

06:13:50

10

NW

06:17:08

63

NE

06:20:25

10

ESE

31 Mar

-1.8

05:24:22

10

NW

05:27:28

36

NNE

05:30:34

10

E

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 has started its next morning apparition. It rises around 4:55a.m. becoming easily visible by 5:30 a.m.  For those awake at this time you will see Venus, Saturn and Mars stretching across the southern skies.  This planetary display nicely represents the path that the planets, Sun and Moon follow.  This path is called the ecliptic.

Mars

Mars is now in the constellation Virgo and will rise around 8:45 p.m. this week.  For those awake around 10:00 p.m. look to the east and you will see a reddish-orange object in the eastern skies.  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

Jupiter is now rising as the Sun is setting.  Look straight up roughly 30 minutes after sunset and you should see Jupiter shining brighter than any star in the sky.  As twilight fades you will see the bright stars Castor and Pollux just north 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. 

Saturn

Saturn is now out of the glare of the Sun.  It rises by 11:08 p.m. and will be an easy target by 12:30 a.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.

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 March is Virgo.  Virgo is one of the twelve constellations of the zodiac.  These constellations were created to track what ancient astronomers thought were wandering stars.  Today we know that the objects they were observing are planets and our modern name for these objects is a derivative of the ancient term Aster Planetae.  What defines Virgo as zodiacal is what is called the ecliptic.  The ecliptic is the path that the Sun, Moon and planets appear to follow in the sky.  Any constellation that crosses this path is considered zodiacal.  Right now Virgo is where you can find Mars rising a little before 10 p.m.  In Greek mythology Virgo was associated with the goddess of justice Astraea and the maiden of the harvest Persephone.  In the tale of Persephone, Virgo represented the daughter of Demeter and was tricked into marrying the god of the underground Hades.  Demeter was so distraught over the loss of her daughter to the underworld she pleaded with the rest of the gods to allow her daughter to return home.  The gods agreed allowing Persephone to return for 1/3 of the year.  The return of Persephone was associated with the spring months in which the return of the maiden would bring life back to the Earth following the dreary winter months.

Virgo is the second largest constellation in the sky.  It contains 20 stars that have been discovered to have planets of their own and it is also loaded with distant galaxies and other deep sky objects.  In Virgo alone there are 12 messier objects most of which many are members of the Virgo Galaxy Cluster.  This month we will go on a tour of Virgo visiting a few galaxies and few other objects of interest. 

Our first object we will talk about is the star 70 Virginis.  Like I said at the end of last month’s night sky update, I wanted to include various stars of interest.  70 Virginis will be the star for Virgo.  This is a yellow dwarf star that has a temperature of about 5400 kelvins which is a bit cooler than the Sun.  It is a little bigger than the Sun at 1.12 solar masses and has a luminosity that is three times higher than the Sun’s.  When all is said and done, this star is similar to the Sun in most regards. 

Another feature that is similar to the Sun and is the reason I am including it in this month’s night sky update is 70 Virginis has a planet.  This was one of the first stars other than the Sun to be discovered to have a planet of its own.  The discovery was made in 1996 and was just one of many that would be discovered over the next few decades.  The current exoplanet count is at 1,690 confirmed and another 3,845 candidates.  We have come a long way since 1996 and based on the current number, it is estimated that the Milky Way which contains an estimated 200 billion stars likely has that many if not more planets.  It has also been discovered that 70 Virginis has a disk of material that lies about 3.4 astronomical units from the star. 

70 Virginis lies about 59 light years away in the northern section of Virgo.  It is a 5th magnitude star that for most will require a pair of binoculars to see.  To find 70 Virginis start at the Big Dipper and follow the curve of the handle to the star Arcturus in the constellation Bootes.  From there continue along the curve until you see a bright blue white star and a bright reddish orange star like object.  The blue white star is Spica and the reddish orange object is the planet Mars.  Next look above Spica and find the bright stars Zeta, Gamma (Porrima) and Epsilon (Vindemiatrix) Virginis.  These stars along with Spica form rhombus shape.  Looking east of Epsilon Virginis about 7 degrees you will see two bright stars that are vertically 4 degrees apart.  The top star is 70 Virginis.  On the map linked below 70 Virginis is the northern most star in the constellation. http://iau.org/static/public/constellations/gif/VIR.gif

The object of the week for March 10 is the giant elliptical galaxy M87. This will be the first galaxy we hunt down this month in the galaxy rich constellation Virgo.  M87 is a member of the Virgo cluster of galaxies which contains between 1800 and 2000 galaxies.  This is the central mass in the larger Virgo Super Cluster which also contains the local group of galaxies the Milky Way belongs to.  M87 was discovered by Charles Messier in 1781 who described it as a nebulous feature.  In 1931 Edwin Hubble included M87 on his list of non-galactic nebula.  By 1956 it was finally recognized as another galaxy and was given a classification of E0 indicating it was an elliptical galaxy. 

An interesting feature of M87 was first discovered in 1918 at the Lick Observatory.  Astronomer Herber Curtis noticed a faint ray of matter extending from the center to beyond the outer edge of M87.  In 1948 the ray was recognized as a bright radio source and in 1967 M87 was also observed to be a bright x-ray source.  All of these observations indicate that M87 has an active galactic nucleus which is powered by a super massive black hole. 

To find M87 first locate the bright star Vindermiatrix (Epsilon Virginis).  From there scan about 8 degrees to the west and you will find M87.  If you use a 50mm pair of binoculars you can just barely see a faint smudge of light if seeing conditions are good.  Also don’t be tricked by another galaxy named M60 which lies about halfway between M87 and Vindermiatrix.  Small telescopes will reveal a small hazy patch of light and telescopes at least 8 inches in aperture will possibly reveal two other elliptical galaxies known as NGC 4476 and NGC 4478.  Large aperture instruments starting in the 10 inch range have successfully resolved the plasma jet associated with M87’s supermassive black hole.  This is a feature that will require excellent seeing conditions and even then it will be difficult to resolve. 

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

For the rest of the month we will explore the area around M87 as there are a number of other galaxies within reach of large binoculars and small telescopes.  This part of the sky is rich in galaxies due to the presence of the Virgo-Coma galaxy clusters and the fact that you are looking away from the Milky Way’s galactic plane.  The spring sky is a bit lack luster when it comes to bright star fields but this lower density of stars is what allows us to find so many of our galactic neighbors.

The object for the week of March 17 is not one but two large galaxies.  Not far from where we found M87 last week there are two large lenticular galaxies called M84 and M86.  Both galaxies lay roughly 50 to 60 million light years away and are member of the Virgo Galaxy Cluster.  Like M87 last week these two galaxies are massive and relatively featureless meaning there is no spiral shape to them.  Due to their lens shape they are caller Lenticular and will appear as slightly elongated ellipses.  Both galaxies are 9th magnitude objects so for most a telescope will be needed to see them. M84 and M86 are also part of a large feature called Markarian’s Chain.  This is a string of galaxies that for an upside down J-shape of stars.  Most of these galaxies range from 9th to 15th magnitude and will be a challenge for most backyard instruments.  The J-shape starts with M84 and M86 and extends up to the north about two degrees.  This string of galaxies forms part of the Virgo Galaxy Cluster.  A good map that has stars down to at least 8th magnitude will be necessary to identify the galaxies.  The free desktop planetarium software Stellarium will also help you find most of these galaxies.

To locate M84 and M86 follow the same directions from last week and find M87.  From there head another two degrees west and you will find M84 and M86.  If you have dark skies and large binoculars you may be able to see these galaxies as two faint fuzzy star like objects but most of us we will need to use a telescope to find them.   http://iau.org/static/public/constellations/gif/VIR.gif

The final object for March is the galaxy M49.  This is another giant elliptical galaxy that lies roughly 60 million light years away.  It is another member of the Virgo Galaxy Cluster and is the cluster’s brightest member at 8.4 magnitude.  It was discovered in 1777 by Charles Messier making it the first member of the Virgo cluster to be discovered and the second galaxy discovered outside the Local Group of galaxies. 

To find M49 first locate the stars Epsilon Virginis (Vindemiatrix) and Delta Virginis.  Start panning to the east from these two stars and look for a large C-shaped group of stars that range from 4th to 5th magnitudes.  If you look about 5 degrees east of the top of the C-shape you will find M87, M86 and M84.  If you follow the bottom of the C-shape roughly 3 degrees to the east you will find M49.  With dark skies a pair of binoculars will resolve M49 as a faint nebulous patch of light.  Small telescope will improve  the view only a little but the galaxy should appear as an egg shaped patch of light.  Follow the link below for a basic map showing the location of M49. 

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

The four galaxies covered this month are just the beginning of the vast amount of galaxies in Virgo and the surrounding area.  Galaxies are beautiful but are very hit or miss depending on your viewing conditions.  If you have a 4 inch or larger telescope spend some time panning through Virgo and her neighboring constellations Leo and Coma Berenices.  There are a number of bright galaxies to be found with the aid of a simple map.  Good viewing conditions and a near new moon will be required.      

Our next Star Party will be held on Friday, April 4, 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 7:00 p.m.  Regardless of the weather on April 4, 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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