December marks the return of Venus in the evening sky. But the brilliant planet is not alone: the long winter nights surrounding the solstice also provide a view of Mars, Jupiter and Saturn… And there’s even a bright meteor shower to top things off.
Venus has been absent from the evening sky for nearly eleven months, but after passing behind the Sun in October, the dazzling planet gradually reappears this December at twilight. Using binoculars first, and then the naked eye, scan the southwest horizon shortly after sunset: Look for a bright point of light piercing the dying glow of day. What’s the earliest date that you can see the Evening Star? As the days pass, the gap between Venus and the Sun will increase, making this exercise increasingly easier; however, a clear view of the horizon is essential. On December 22, about 30 minutes after Sunset, see if you can spot a thin lunar crescent 6 degrees to Venus’s right.
The Evening Star’s return makes it easy to overlook the discreet presence of Mars in the same region of sky. In fact, the Red Planet is still visible early in the evening and is easy to spot in the twilight, around 6:00 P.M., about 15 degrees above the southwest horizon. On December 24, two days after it approaches Venus, the crescent moon will appear 6 degrees to the right of Mars. Since the Moon will be higher in the sky, the faint glow of earthshine will be evident. (This is Earth’s light reflected onto the otherwise dark part of the lunar face). Earthshine is outstanding to see with the naked eye, and even more impressive through binoculars.
Mars sets in the southwest around 7:30 P.M., but Jupiter arrives on the scene a bit later in the evening. At the beginning of December, the brilliant planet rises in the east-northeast around 10:30 P.M. and culminates in the south at about 5:00 A.M.; toward month’s end, it rises around 8:30 in the evening and culminates around 3:00 in the morning. During the night of December 11 to 12, the waning gibbous moon will pass beneath the giant planet. Jupiter is currently in Leo, a little to the right of Regulus, though it begins to retrograde on December 9. For the following few months, the brilliant planet will appear to retrace its path among the stars, moving away from Regulus and heading westward into Cancer. The start of Jupiter’s retrograde movement signals the approach of the planet’s next opposition on February 6, 1015.
Saturn is also back after its passage behind the Sun. The ringed planet re-emerges at dawn, low on the southeast horizon. On the morning of December 19, look for a thin lunar crescent to appear 5 degrees above Saturn.
A classic meteor shower
In Quebec, December nights are much less comfortable than those of August, which makes it easy to understand why the Geminid meteor shower is less widely known than the famous Perseids. That’s unfortunate because the Geminids are reputed to be more abundant than their summer cousins; they are also notably slower, which makes them easier to follow.
This year, the Geminids reach their maximum around 7:00 A.M. (EST) on the morning of December 14, so one can expect a very nice show on the evening of the 13th. Under an ideal sky, free of light pollution, close to fifty meteors an hour should be visible before the last quarter Moon rises around 11:30 P.M. The evening of the 14th will be equally favourable; the Moon will rise half-an-hour after midnight. One might also consider observing the Geminids on the preceding and following evenings, though they will be less abundant.
The longest nights
The winter solstice will occur on December 21 at 6:03 P.M. (EST). On that day in Montreal, the Sun will rise at 7:31 and set at 4:14, resulting in a total of 8 hours and 43 minutes of sunlight. This represents the shortest day of the year, and consequently, the longest night. However, it does not correspond with the earliest sunset, nor the latest sunrise, due to the difference between solar time (the time indicated by sundials) and civil time (as indicated by clocks) — a difference that changes rapidly at this time of year. Over the space of a few weeks, the total number of daylight hours shifts, by several minutes, toward the second half of the day.
In Montreal, the earliest sunset occurs at 4:11 P.M. around December 10, several days before the solstice; the latest sunrise occurs at 7:34 A.M. around January 2. A similar shift can be observed everywhere throughout mid-northern latitudes.
The long solstice nights of winter offer ample opportunity to appreciate the passing stars. In the evening, the autumn constellations gradually yield to those of winter. Canis Major, with its brilliant star Sirius — the brightest in the sky — is the last constellation of the winter hexagon to rise in the southeast: It appears completely above the horizon by 11:00 P.M. at the beginning of December, and around 9:00 P.M. toward month’s end. But when dawn arrives, around 6:00 in the morning, it’s the springtime constellations like Leo, Virgo, and Ursa Major that culminate and occupy the centre of the celestial stage.