The elusive planet Mercury makes an appearance in the evening sky late in the month. After passing superior conjunction in mid-November, the speedy planet moved into the evening sky, although setting shortly after the sun. As Mercury approaches its greatest separation from the sun, it appears higher in twilight. By month’s end it sets nearly 90 minutes after the sun. At this time, it sets as twilight ends, making the planet visible only during twilight. The chart above shows Mercury at 5 p.m. CST on December 25, just 35 minutes after sunset (from the Chicago area). To see Mercury, find a clear southwest horizon and use binoculars to locate the planet low in the sky.
Mercury’s Evening Appearance, December 2015