Mars shines at its most brilliant this month as it reaches opposition. The bright orange planet is in view all night. Venus and Mercury spend most of December huddled together in the evening twilight, with Mercury changing brightness significantly during the month. The stars of winter begin to take over the evening sky, with Orion climbing across the south, trailed by Sirius, the brightest star in the night sky.
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In the Sky This Month
December 6: Mars II
Look for Mars low in the east-northeast as night falls, to the lower left of the Moon, and climbing high across the sky later on. It looks like a bright orange star. Only the Moon and the planets Venus and Jupiter outshine it.
December 7: Mars III
Bright Mars will vanish tonight, blocked from view by the Moon. The vanishing act will be visible from all of the U.S. except the southeast, Hawaii, and most of Alaska. The timing depends on your location. At most, the Moon will cover Mars for a bit more than an hour.
December 8: Earliest Sunsets
The shortest day of the year, the winter solstice, is a couple of weeks away, but most of the United States is seeing the earliest sunsets of the year. The days are still getting shorter, though, because the Sun will continue to rise later until after the solstice.
December 9: Venus Rising
The planet Venus is returning to view. It’s quite low in the southwest in the early evening twilight and will climb a little higher each night throughout the month, beginning a long reign as the brilliant Evening Star.
December 10: Moon and Gemini
Pollux, the brighter twin star of Gemini, is close to the left of the Moon as they climb into view in mid-evening. The other twin, Castor, is above Pollux.
December 11: Moon at Apogee
The Moon will be farthest from Earth tonight for its current orbit, at a distance of almost 252,200 miles, which is more than 13,000 miles farther than average. That makes the Moon look a little smaller and fainter than average.
December 12: Geminid Meteors
The Geminid meteor shower is expected to be at its best tomorrow night, peaking before dawn on Wednesday. Unfortunately, the Moon will be in view then, washing out the fainter meteors. But many of the Geminids are fairly bright, so the shower is worth a look.
Full December 7, 10:08 pm
Last December 16, 2:56 am
New December 23, 4:17 am
First December 29, 7:21 pm
Times are U.S. Central Time.
Apogee December 11
Perigee December 24
The full Moon of December is known as the Long Night Moon or Moon Before Yule.