This is the Dudley Observatory Skywatch Line for Wednesday, January 24th, and Thursday, January 25th, written by Louis Suarato.
The First Quarter phase of the Moon occurs at 5:20 p.m. Wednesday. At 6 p.m., the Moon will be directly over the southern horizon, and it will set very close to midnight. During this lunar phase, the Sun is at a 90 degree angle to the Moon, and the Moon lags behind the Sun by 6 hours. It rises around noon, is highest at 6 p.m., and sets near midnight. The First Quarter phase doesn’t derive its name from the quarter of the day movement though. The First Quarter Moon is ¼ through its cycle at this time. The angle of the Sun casts long shadows along the Moon’s terminator, so take advantage of this time to explore its highlighted details on this line between lunar day and night. Thursday night, look for the Pleiades star cluster to the upper left of the waxing gibbous Moon.
Four easily visible planets will rise overnight, beginning with Jupiter at 1:56 a.m., in the constellation Libra. Mars, also in Libra, follows at 2:42 a.m.. Saturn rises at 5:25 a.m. in Sagittarius. Mercury, currently at aphelion, its furthest distance from the Sun, rises at 6:43 a.m., about a half hour before sunrise. The overnight sky also features Comet 94P/Smirnova-Chernykh. Discovered by Tamara Mikhajlovna Smirnova in March 1975, this comet is at perihelion, its closest distance to the Sun during this visit, at a distance of 3.54 astronomical units, or 3.54 times the distance of the Earth to the Sun. This comet has an orbital period of 8.53 years, and is expected to peak in brightness on March 11. Look about 6 degrees below Leo’s second brightest star, Denebola for this comet.