2009 December Skies


The Moon is full on December 2. Just like last month, this one opens with the Moon gliding through the Seven Sisters (Pleiades). When people see this cluster up close, they realize that there is far more to it than can be seen with the naked eye. Nearly 1000 stars nestle in the glow of a blue dust cloud (nebula), dominated by about 14 young, hot blue stars. The popular name comes from the Greek mythology of the Seven Sisters – the nine brightest stars, including two for their parents. Getting back to the Moon, a partial eclipse occurs on the last day of the year in some parts of the world. This is also the second full Moon of the month, a so-called Blue Moon.
Mercury is visible throughout December in the western sky just after sundown, an Evening Star like its running partner, Venus.
Speaking of Venus, that’s all we can do is speak about it, as it is too close to the Sun for viewing.

Mars is in Cancer, The Crab, all month, being joined by the old Moon on the 9th. Mars slows to a stop in its motion against the starry backdrop on December 21, and then begins retrograde motion for about three months. Remember that it’s us also moving that causes this illusion of apparent “backward” motion – the planets don’t really change direction in their orbits.
Jupiter, along with Uranus and Neptune, is “chasing the Sun down.” By mid-February, Jupiter will be behind the Sun; Neptune will have passed the gas giant planet on December 20, leading the parade, with Uranus bringing up the rear. During the month, Jupiter dominates the southern sky right after sundown, making a grand opportunity to view and study the Galilean moons.
Saturn is in the constellation Virgo, The Maiden, rising about 2 a.m. and prominent in the southern sky just before daybreak. Saturn’s rings are showing much more of their northern exposure, having passed through the plane-crossing event last September. A very old Moon glides by the Ringed Planet on the morning of the 9th.
As the International Year of Astronomy winds down, people all over the world are finding ways to keep the impetus of this wonderful year of partnership and collaboration going on into the future. The program “100 Hours of Astronomy” promises to be one of those events that will continue on an annual basis. Watch for notice of it in the spring.

James Edgar has had an interest in the night sky all his life. He joined The Royal Astronomical Society of Canada in 2000 and quickly became involved in the Society. He is Editor’s Assistant and a contributor to the renowned Observer’s Handbook, Production Manager of the bi-monthly RASC Journal, and is the Society Secretary. He celebrates IYA2009 in Melville.