The moon begins December entering last-quarter phase Dec. 3, a little less than two degrees away from Jupiter in the early morning sky. Dec. 5, Mars is within 0.1 of a degree, an occultation in the Southern Hemisphere. The following day, Dec. 7, Venus is occulted for viewers in North America, another early morning event.
Implicit in this is that the three Solar System bodies are visible in the eastern dawn sky — Jupiter, Mars, and Venus — so all four bodies can be seen at once in the early part of the month. Later on, Uranus will join the moon just after first quarter Dec. 19, an occultation in Antarctica. The bright star Aldebaran in Taurus, is occulted Dec. 23 for eastern Canada viewers. For the west, it’s a close conjunction. The moon is full Dec. 25, and Jupiter sidles up close again Dec. 31.
Mercury is well placed in the western evening sky after Dec. 7, reaching maximum elongation Dec. 29.
Venus shines brightly in the eastern twilight before the rising sun. The occultation mentioned above, even though occurring during the daytime, should be visible because Venus is so bright. This is a great opportunity to see planetary motion in action, as the moon glides in front of another Solar System body.
Mars is one of the three bodies noted above involved in the close encounters with our satellite. Watch for a grouping and close approach Dec. 6.
Jupiter becomes visible in the east in late evening, residing in the constellation Leo, The Lion. It’s the first to lead the parade of planets into the dawn sky. Watch for a close approach to the moon Dec. 3.
Saturn has been behind the sun for some weeks, and makes an appearance late in the month in the dawn twilight.
Uranus is in Pisces in the evening, a good position for observing. The moon passes in front of the giant gas planet Dec. 20 for some viewers, but not here in North America.
Neptune is a telescopic object in the western evening sky, setting in late evening.
The night of Dec. 14 sees the peak of the Geminid meteor shower. Predictions are for approximately 120 meteors per hour, under ideal conditions.
— 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.
