The year’s first month ends with perhaps the best skywatching show of the year, as the Moon passes through Earth’s shadow, creating a total lunar eclipse. The nights leading up to the eclipse provide plenty of beautiful sights, though. Mars and Jupiter are climbing higher into the morning sky, and snuggle close together for several days. Orion climbs high across the south during the evening hours, with its belt pointing toward Sirius, the brightest star in the night sky.
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In the Sky This Month
January 23: Mizar and Alcor
Look northeast in late evening for the Big Dipper. The handle points toward the horizon, with the bowl high in the sky. The second star from the end of the handle is Mizar. If you look carefully, you might see its faint companion, Alcor.
January 24: Hot Giant
The Northern Cross is in the west and northwest at nightfall. A star system near its center is home to the hottest planet yet discovered. Dayside temperatures on KELT-9b soar to 8,000 degrees Fahrenheit, which is hotter than most stars.
January 25: Second-Chance Planets
Gemini is in the east at nightfall. The constellation is marked by its two brightest stars, Pollux and Castor, which represent Gemini’s twins.
January 26: Moon and Aldebaran
Aldebaran, the brightest star of Taurus, stands to the lower left of the Moon at nightfall. Over the following few hours the Moon will move ever closer to the star. At their closest, they will be separated by less than the width of your finger at arm’s length.
January 27: Pollux
The brightest star with a known planet climbs high across the sky on winter nights. Pollux is the brighter of the “twin” stars of Gemini. It is about a third of the way up the eastern sky as night falls, with the other twin, Castor, to its upper left.
January 28: Castor
Castor, the fainter of the twins of Gemini, is about a third of the way up the eastern sky at nightfall, close to the upper left of Gemini’s brighter twin, Pollux. Tonight, the Moon will stand to the upper right of the twins.
January 29: Leo Rising
Leo, the lion, springs into the evening sky this month. Its brightest star, Regulus, rises around 7:30 or 8 p.m., with the body of the lion following over the next hour or two. Denebola, the star that marks its tail, climbs into good view by 10 p.m.