Dec 03

What’s Up in the Sky

What’s Up in the Sky – December, 2012

December a Good Month for Planets

If we are fortunate enough to have some clear skies around dawn and dusk next month we will be able to enjoy several bright planets.  The most obvious and easiest to observe is Jupiter, which rises at sunset at the beginning of the month and two hours before sunset by the end.  Check out the southeastern sky the next few nights and you will see the almost-full Moon pass close below the Pleiades and Jupiter.  This close encounter is repeated in December when, on Christmas night, the Moon will be right next to Jupiter in the constellation Taurus, the Bull.

The fact that Jupiter is above the horizon most of the night means this is a good opportunity for some telescopic observing of the planet.  It’s always interesting to see the Great Red Spot and cloud bands on the planet itself as well as its four bright moons,  If you are lucky (or have done some web research) you may even witness one of these moons pass in front of or behind the planet.  It is even possible for skilled observers to be able to see the moons’ shadows cast on the cloud tops.

Mars is also visible after sunset low in the southwest.  The best time to spot it will be on the evenings of December 14 and 15 when it will be close to a thin crescent Moon.  Look just to the left of the Moon on Friday and below it on Saturday.

Four planets can be spotted before dawn during the first two weeks of  December.  Look for Jupiter setting in the northwest while Mercury, Venus, and Saturn can still be seen in the southeast.  The problem, of course, is knowing how to identify these last three, but that’s why you read this column.

Look low in the southeast about an hour before sunset (between 7:00 and 7:30 a.m.).
Venus is by far the brightest. object in this part of the sky.  Make a fist and hold it at arm’s length toward Venus.  Mercury will be less than the apparent width of your fist to the lower left of Venus and Saturn will be a little over two fist widths to its upper right.

If you are still not sure, look each morning from Sunday through Tuesday, December 9 – 11.  The thin, crescent Moon will be right below the star Spica on the 9th, Saturn on the 10th and Venus on the 11th.  Even seeing it on one of those days should help you identify what’s up in the sky.

This month in history:
Dec. 7:    Galileo spacecraft enters Jupiter’s atmosphere – 1995
Dec. 11:    First auction of Soviet space hardware and artifacts – 1993
Dec. 14:    Gene Cernan, Apollo 17 astronaut, is last human to walk on Moon – 1972
Dec. 20:    Founding of Mt. Wilson Solar Observatory – 1904
Dec. 24:    Apollo 8 astronauts give us inspirational moment from lunar orbit – 1968
Dec. 25:    Isaac Newton born – 1642