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The Sky This Week, 2010 January 26 - February 2

Groundhog Day, and Mars Attacks!
Mars, 2010 January 14, 03:43 UT
South at top. Note prominent north polar ice cap

The Moon waxes in the late evening sky this week, brightening snowy landscapes as she beams down from her perch high among the winter stars.  Full Moon occurs on the 30th at 1:18 am Eastern Standard Time.  This Full Moon is popularly known as the Wolf Moon, Snow Moon, or Hunger Moon, each of which bears connotations of the depths of winter’s icy grip.  Luna starts the week close to the star El Nath, high in the sky during the late evening hours.  She passes near Castor and Pollux, the Gemini Twins, two nights later.  On the 29th Luna lies just six degrees south of bright ruddy Mars among the faint stars of Cancer, the Crab.  By the week’s end she dives toward the southern reaches of the ecliptic, rising late in the evening with the fainter stars of spring.

The week ends with one of my favorite astronomical observances, Groundhog Day, which has its roots well-entrenched in ancient folklore.  Originally celebrated among Celtic people as “Imbolc”, it was traditionally the time that ewes started lactating in anticipation of the birth of their spring lambs.  As Christianity spread into Europe, the day became significant as “Candlemas”, the 40th day after Christmas, when the infant Jesus was presented at the temple by Joseph.  Both traditions incorporated watching the behavior of hibernating animals as a gauge of the coming arrival of spring.  They were also days that happened to mark the mid-point of the astronomical season of winter, so-called “cross-quarter” days.  In America, the weather forecasting prowess of hibernating animals was introduced by German immigrants to southeastern Pennsylvania in the 1840’s.  The groundhog replaced the badger in the imported tradition, but the theme was the same.  If the groundhog saw its shadow on Groundhog Day, it meant six more weeks of winter.  No visible shadow portended an early spring.  Of course, there are now many groundhogs in many locations in the U.S. and Canada, and local weather conditions can influence the outcome of local observations.  One thing that is always certain is that, astronomically, winter ends on the vernal equinox, which falls on March 20th at 12:32 pm EST this year.

Giant Jupiter can still be glimpsed in evening twilight, but he’s rapidly losing ground to the relentless Sun.  As the week opens he sets two hours after the Sun.  By the week’s end he loses another 20 minutes to Old Sol, setting just after the end of evening twilight.  He’ll pass behind the Sun on February 28th, and emerge into morning twilight later in March.

The warm glow of Mars now takes over as the night’s brightest planet.  This is the best week of the year to observe the red planet, since he will be closer to the Earth on the night of the 27th than he will be from now until the spring of 2014.  That said, this is not a particularly favorable opposition since Mars is close to his most distant point from the Sun, but a modest telescope under steady skies can still pick out quite a bit of detail on his 14 arcsecond disc.  In particular, his north polar icecap is very prominent and should be visible in a good four-inch instrument.  Six- to eight-inch telescopes should reveal some of the darker features that dominate the planet’s southern hemisphere.  Mars reaches opposition on the 29th, when he will be well-placed in the sky from dusk to dawn.
Saturn is following hard on the heels of Mars.  The ringed planet is now located among the stars of the sprawling constellation Virgo, and by the week’s end he rises at 9:30 pm.  If you’re up late looking at Mars, give Saturn a glance before you pack up for the night.