December 1999

by Steve Stefanik

Five planets can be seen with just your eyes as December begins, three in the evening and two in the morning.

The planet Mars can still be seen low in the southwest among the dim stars of the constellation Capricornus. Look for the red-orange first magnitude planet before it sets by 9:00 p.m. local time. On the night of the13th look for Mars within a degree of +5.9 magnitude blue-green Uranus.

On the same night, the Geminid meteor shower peaks. Although the Geminids traditionally have fewer meteors per hour than the recent Leonid meteor shower of this past November they generally produce bigger and brighter meteors. The Geminids appear to radiate from the constellation Gemini which is high in the east by 9:00 p.m.

The planets Jupiter and Saturn are still at center stage high in the south by mid-evening. Brilliant Jupiter at magnitude -2.7 is the brightest object in the nightsky except for the moon so you should have little trouble locating it. Saturn is somewhat dimmer at zero magnitude but much brighter than any of the stars in the vicinity and trails Jupiter (to the left) by one hand-span at arms length. Through just about any telescope you can see the bands and zones of Jupiter’s turbulent atmosphere and its four largest moons as well as the rings of Saturn of course. The moon joins the pair on the nights of the 17th through the 19th.

The remaining two planets Mercury and Venus rise in the eastern sky in the early hours of the morning. Venus rises by 4:00 a.m. among the stars of the constellation Virgo and lies about 4 degrees from Virgo’s brightest first magnitude star Spica but moves quickly into the nearby constellation Libra by mid-month.

The planet Mercury makes its best appearance of the year this month rising more than an hour before the sun among the stars of the constellation Scorpio. If you have difficulty locating it, the waning gibbous moon will be within 5 degrees to the northwest it this morning.

The winter solstice occurs on December 22 at 2:44 a.m. Eastern Standard Time when the sun stops its southward migration and begins inching northward once again adding precious minutes of daylight to each passing day.