Looking for a sky event this week? Check out our full Sky This Week column.
December 4: December’s Full Cold Super Moon
Our view of Mercury has continued to improve over the past few days. Rising almost two hours before the Sun, the little planet appears 7° high an hour before sunrise in the east. It shines at magnitude –0.3, an easy-to-find naked-eye object in the slowly brightening sky. Through a telescope, its disk now appears 54 percent lit, a bigger chunk receiving sunlight compared to earlier in the week and a tidy explanation for its increase in brightness.
Mercury will reach its greatest elongation west of the Sun in just two days, when it will stand 21° from our star. High above it and slightly to the left is magnitude –0.1 Arcturus in Boötes, while magnitude 1.0 Spica sits to Mercury’s upper right. See how long you can follow these stars as well as the planet into the encroaching dawn.
Bright Venus (magnitude –3.9) chases Mercury up into the predawn sky, now rising about 30 minutes before the Sun. There’s a brief opportunity to view it, but only if your horizon is clear. Venus is still 99 percent lit and virtually indistinguishable from a full phase.
As always, make sure to put away any optics at least several minutes before sunrise from your location.
Sunrise: 7:07 A.M.
Sunset: 4:34 P.M.
Moonrise: 5:05 P.M.
Moonset: 8:14 A.M.
Moon Phase: Waning gibbous (98%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.
