The month begins with the moon just below Saturn (an occultation in the extreme south of Antarctica) and to the west of Mercury in the early morning eastern sky.
New moon is Dec. 3, so observation of the slender crescent Dec. 1 will be a serious challenge. A few days later, the moon is an evening object, right above Venus on Dec. 5. Full moon is Dec. 17, the smallest apparition of 2013, as our satellite is furthest from us in its orbit. Dec. 19, Jupiter joins forces with the moon in the eastern evening sky right after sunset. Mars joins the third-quarter moon in the east on Christmas Day. Later on, Spica Dec. 27 and Saturn (again) Dec. 28 are occulted by the moon, but these events are only visible from elsewhere. For us, the distant objects are lunar close companions only.
Mercury is visible in the morning sky for the first week or more of December as it rounds behind the sun for the remainder of the month.
Venus shines brightly in the western evening sky for a couple of hours after sunset as it rounds in its orbit in front of the sun later in January. As noted above, watch for the thin crescent moon above Venus Dec. 5.
Mars appears in the constellation Virgo, the maiden, shortly after midnight. The Red Planet is getting brighter with each passing day, as it and Earth get closer in their mutual orbits. Early April 2 is when the two planets are their closest (Mars at opposition). Astronomers are already getting clear images of Mars, able to discern surface features.
Jupiter rises in the evening, crossing the sky all through the night. Since Jupiter orbits the sun in a little over 11 years, it spends nearly a year in each of the zodiac constellations. Right now, the giant gas planet is in Gemini, the twins. Watch for the nearby waning gibbous moon on the night of Dec. 18/19.
Saturn is in the morning sky, and, as mentioned above, is occulted twice this month, but only in remote locations. For us, we see the moon very close to the ringed planet.
We find Uranus retrograding in Pisces, well placed for viewing in the evening sky.
Neptune, too, is in the same region of sky as Uranus, rising about an hour earlier. The very distant planet requires large binoculars or a telescope for observations.
Winter Solstice is on Saturday, Dec, 21. And, if Comet ISON lives up to the hype, this is when it should be at its brightest, visible in the morning sky before sunup.
- 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 assistant editor 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.
