Seeing Stars with James Wooten: March 2012

March 2012 features all five visible planets, visible at convenient evening hours!

Astronomy Day 2008

Venus continues to appear higher and higher in the sky each night, outshining everything but the Sun and the Moon.  Look for it in the west at dusk.  It is also still approaching Jupiter each night as March begins.  On the first few nights of March, Venus is just over 10 degrees below Jupiter in the west.  However, Venus continues to close that gap until March 13, Venus and Jupiter are side by side, with Venus on the right.  After that, Venus pulls away, appearing higher than Jupiter in the west at dusk.  Jupiter outshines everything in our sky except the Sun, the Moon, and Venus.  Venus and Jupiter thus make a spectacular pair in the west this month.

Mars has joined Jupiter and Venus as an evening object.  Face east at dusk and look for the brightest point of light in that direction.  Although not as bright as Venus or Jupiter, Mars has brightened enough to rival Sirius, the brightest star we ever see at night. On March 3, Earth passes between Mars and the Sun, putting Mars in our sky literally all night long (an alignment called opposition).

Mercury is ordinarily too close to the Sun to observe; only rarely is it far enough from the Sun to be still up after sundown.  Early March 2012 is one of those rare times, however.  During the first two weeks of March, look for Mercury low in the west at dusk, between Venus and the point of sunset.  Mercury is highest in the sky on March 5 and gets a little harder to see each day after that.

Saturn becomes a late evening object this month.  Look in the south southeast beginning at about 10:00 pm on March 1, and by 8:40 (just after twilight ends) on March 31.  Saturn is near the star Spica.  (From the Big Dipper’s handle, arc to Arcturus and speed on to Spica).

Big Dipper in a big sky

Brilliant winter stars continue to dominate the southern sky at dusk.  Orion, the Hunter, is almost due south.  His two dogs, represented by Sirius and Procyon, are to his left.  Above Orion is Taurus, the Bull with Aldebaran as its eye. Gemini, the Twins, are to Orion’s upper left.  Leo, the Lion, is rising in the east.

Below Sirius, just above the southern horizon, is a star second only to Sirius in brightness.  This is Canopus, which marks the keel (bottom) of the legendary ship Argo Navis.  Canopus is so far south, in fact, that most Americans never see it.  From the Gulf Coast, however, Canopus does rise.  February and March are the best months to see it at dusk.

Moon Phases in March 2012:

Full                               March 8, 3:41 am

Last Quarter                  March 14, 8:26 pm

New                              March 22, 9:38 am

1st Quarter                     March 30, 2:41 pm

At 12:13 am on Tuesday, March 20, the Sun is directly overhead at the equator.  This, then, is the vernal (spring) equinox, marking the official beginning of spring in the Northern Hemisphere.  In the Southern Hemisphere, summer turns to fall.

Visit www.hmns.org for the latest planetarium schedule.

On most clear Saturday nights at the George Observatory, you can hear me do live star tours on the observation deck with a green laser pointer.  If you’re there, listen for my announcement.

Go Stargazing! December Edition

The ‘main event’ of December evenings occurs in the southwest at dusk, where you can watch Venus pull away from Jupiter.  Look southwest right as night falls for the two brightest things there except for the Moon.  The brighter one low in the southwest is Venus, which outshines everything else in the night sky.  Jupiter is the dimmer of the two, although it still outshines all the stars we ever see at night.  Venus and Jupiter begin the month about 2 degrees apart (your finger at arms length blocks about 1 degree.)  However, Venus will extend that gap quite noticeably each night, until it appears high above Jupiter on December 31. 

Mercury emerges from the Sun’s glare in time to form a nice pair with Jupiter on New Year’s Eve.  As you prepare to ring in 2009, take a moment to look at Mercury just to Jupiter’s left in late twilight.  That same night, the Moon will be near Venus. Saturn can be found high in the south at dawn.  Mars is lost in the Sun’s glare this month, and will remain out of sight into 2009.  It is directly behind the Sun (in conjunction with the Sun) on December 5.

Orion no céu
Creative Commons License photo credit: giumaiolini

The enormous Summer Triangle, consisting of the stars Deneb, Vega, and Altair, sets in the west.  The Great Square of Pegasus is overhead at dusk.  The star in its upper left hand corner is also the head of Andromeda.  Facing north, you’ll see five stars in a distinct ‘M’ like shape—this is Cassiopeia, the Queen.  Her stars are about as bright as those in the Big Dipper, and she is directly across the North Star from the Dipper.  In fall and early winter, while the Dipper is low and out of sight, Cassiopeia rides high.

Dazzling Orion rises in the east, reminding us that winter is on the way.  His belt points up to Aldebaran, the eye of Taurus the Bull.  By 9 pm tonight (7 pm by New Year’s Eve), the Dog Stars Sirius and Procyon will have risen below Orion in the east.  Sirius is the brightest star we ever see at night. 

Moon Phases in December 2008:

1st Quarter         December 5, 3:25 pm
Full                     December 12, 10:38 am
Last Quarter        December 19, 4:30 am
New                    December 27, 6:22 am

At 6:04 am on Sunday, December 21, the Sun is directly overhead at the Tropic of Capricorn, meaning that the North Pole is tilted as much as possible away from the Sun.  This is the winter solstice.  For people in the Northern Hemisphere, December 21 has less daylight and more night than any other day of the year. 

Sunset at Appalachian Trail
Creative Commons License photo credit: Pardesi*

However, the earliest sunsets occur on December 1 and 2.  We are already close enough to the solstice that the Sun’s apparent path across the sky on December 21 is only slightly lower than on any other day this month.  Meanwhile, Earth is about to make its nearest approach to the Sun, called perihelion, in January.  As a result, the Earth is speeding up.  The effect isn’t much (Earth’s orbit is nearly circular), but it’s enough to make both sunrise and sunset a little later each day this month and next.  With the Sun’s apparent height in the sky not changing that much in December and January, the small effect of Earth’s acceleration near perihelion dominates.  Since most of us sleep through sunrise and witness sunset, the days seem be slightly lengthening between the beginning of the month and the 21st, although they are actually getting slightly shorter.