December begins with the moon just past full phase. We get a few rapid close calls Dec. 9 to 12 - the star Spica is within a degree (an occultation in the Southern Hemisphere) Dec. 9; Saturn and the moon are four degrees apart the following night; Venus will be within 1.6 degrees Dec. 11; and Mercury is just over one degree away Dec. 12 (another occultation, but only in Antarctica). On the evening of Dec. 26, Jupiter is just a half a degree away, occulted in the Southern Hemisphere. The moon is full Dec. 28.
Mercury is a morning object, the best apparition for Northern Hemisphere observers during the first week. Venus will be close by from Dec. 4 to 15, and the moon glides by Dec. 12. If you've never before seen Mercury, this is a good opportunity, as Venus can be your guide to finding the elusive planet. Dec. 17, Mercury will be just six degrees north of Antares, the red, giant, carbon star in Scorpius.
Venus shines brightly in the east before dawn all through the month. A slender crescent moon passes within 1.6 degrees Dec. 11 and Antares shares the sky Dec. 23, six degrees south of the "Morning Star." Look for nearby Mercury during the first part of the month.
Mars is a difficult object to observe, appearing low in the west just before sunset and setting shortly after.
Jupiter is a glorious sight through even a small scope or binoculars. Larger telescopes reveal the horizontal stripes on the gas giant planet. Who can watch the Galilean moons in their daily dance without gaining a sense of wonder at our Solar System? Jupiter rises in the east after sunset, crosses the sky all night, setting in the west at dawn. Watch for the close brush with the moon on Christmas Day evening.
Saturn is well placed for viewing in the eastern dawn sky, just a bit east of Spica and above Venus, which rises shortly after. The two planets gradually move apart and are split by the thin crescent moon Dec. 10. Then, Mercury rises slightly east of Venus, making a row of the three planets, plus the moon. This could be a good photo opportunity.
Uranus rises in mid-afternoon, so will be straight south at sunset in Pisces, The Fish.
Neptune rises about an hour earlier than Uranus, leading the pair across the sky in the constellation Aquarius, the Water Bearer.
The Geminid meteors peak on the evening of Dec. 13. Look northeast for the radiant just above the two bright stars in Gemini, Castor and Pollux.
- James Edgar has had an interest in the night sky all his life. He joined the Royal Astronomical Society of Canada in 2000 and is now editor's assistant and a contributor to Observer's Handbook, production manager of the bi-monthly RASC Journal and the society's national secretary. He was given the RASC Service Award at the 2012 general assembly in Edmonton.
