December 1997

by Steve Stefanik

On the night of December 2, four planets can be seen along with a three-day old crescent moon in the southwest as the sun sets. Look for the planet Mercury first, just 7 degrees above the western horizon and 7 degrees to the left of where the sun goes down. It will appear as a -0.2 magnitude yellow star but through binoculars you may be able to make out its "quarter moon" phase. Next, look for the sliver of the crescent moon 22 degrees above the horizon. Just below and to the left of it you will find the first magnitude red planet Mars. Just above and to the left of Mars you will spot the brilliant planet Venus. It will be hard to miss being the brightest object except for the moon at magnitude -4.7 and highest it ever gets, 25 degrees above the horizon. Jupiter will be the other bright object higher and to the left of Venus although not as bright as Venus being -2.2 magnitude.

Mars will play tag with Venus throughout the month of December as Venus slows its eastward motion while Mars continues to move eastward. The pair will come within 1 degree of each other. Venus begins to move westward on Christmas day when Mars passes within 0.6 of a degree of Uranus on December 26. Uranus is a dim 6th magnitude but the pair can be spotted in the same field of view through binoculars or a low power telescope. Neptune is nearby but will be difficult to spot at magnitude +8.0 without the aid of either.

You can see Saturn this month as well, high in the southeast among the stars of Pisces at nightfall. At +0.6 magnitude it is relatively easy to spot beause there are no stars brighter than first magnitude in this area of the sky.

This is also the month of the annual Geminid meteor showers. Even though it peaks on the night of the 13th during the full moon, activity begins on the 7th and continues through the 17th. Also on the night of the 13th, the full moon occults the first magnitude star Aldebaran, the eye of the bull, in the constellation Taurus which rises in the east early in the evening along with the familiar winter constellation Orion just before Gemini. Other tell-tale wintertime constellations of Pegasus and Perseus are high in the sky overhead while the "Summer Triangle" constellations of Aquilla, Lyra, and Cygnus are setting.