The month begins with the moon at waxing gibbous phase, and Uranus is just 1.2 degrees south, just like the month previous during the lunar eclipse of Oct. 8. Four days later, Dec. 5, Aldebaran, the bright star in Taurus, is just over a degree away. And, the next day is full moon. By Dec.11, Jupiter rises in the east around 11 p.m. with the waning moon a couple of degrees away. Dec. 12, the moon reaches apogee, the furthest from Earth in its monthly elliptical orbit. Saturn and the moon meet up Dec. 19, a morning event that could make for a good photographic opportunity, with the slender waning crescent beside the Ringed Planet. By Dec. 22, Venus is a mere six degrees south of Luna; perigee (closest approach) is Dec. 24; Mars is six degrees south on Christmas Day; and Uranus is back to a close approach Dec. 28, an occultation in the northwest Pacific.
Mercury is behind the sun for most of the month (superior conjunction), appearing in the western evening sky late in December. The speedy planet and Venus pair up in the evening twilight, but you have to be quick, and sharp-eyed, or you'll miss them.
Venus shows up in the western evening twilight early in the month, climbing higher each evening. By about the last week of the month, Mercury is right below the so-called Evening Star. You might catch the slender crescent moon, Venus and Mercury together Dec. 23, right at sundown.
Mars appears low in the southwest evening sky, well above Venus and Mercury later on. Dec. 24, the crescent moon brushes by the Red Planet. Potentially, you could see three planets and our satellite all lined up in the west at sundown.
Jupiter rises in the constellation Leo, The Lion, in late evening as the month opens. Off to the west, Sirius, the brightest star in the night sky, rises about the same time, preceded by Orion, the Hunter. Watch for the moon beside the giant gas planet on Dec. 11.
Saturn appears over the eastern horizon just before daybreak, rising earlier with each passing day. The moon closes in Dec. 19 for a nice pairing.
Uranus has a double encounter with the moon, once Dec. 1 and again Dec. 28 (a lunar month later, of course). The second close approach is an occultation, where the moon passes in front of the other body. This particular cover up is visible from Japan, the Arctic Ocean, northern Canada and Alaska.
Neptune, the barely visible planet, even in a telescope, rises in mid-afternoon, crossing the sky in the constellation Aquarius, and setting in late evening.
- 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 the society's president, assistant editor and a contributor to the Observer's Handbook, production manager of the bi-monthly RASC Journal. He was given the RASC Service Award at the 2012 General Assembly in Edmonton.
