A pair of planets pushes up into the western sky shortly after sunset this month. Venus, the brilliant Evening Star, is beginning a long run in the evening sky. Mercury reaches its farthest point from the Sun in our sky this month, and will be dropping back toward the Sun by the end of the month. It is a difficult planet to watch, so its proximity to Venus will help it stand out.
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In the Sky This Month
March 20: Winter Circle
Spring arrives in the northern hemisphere today, but the most prominent stars of winter remain in good view. They form a big loop known as the Winter Circle, which is in the southwestern quadrant of the sky this evening.
March 21: Coma Berenices
The constellation Coma Berenices, which represents the hair of a legendary queen, is well up in the east by mid-evening. It is about half way between the bright stars Arcturus and Regulus, which highlight the eastern sky.
March 22: Moon and Aldebaran
Aldebaran, the bright eye of the bull, stands just below the Moon at nightfall, and leads the Moon down the sky later on. Aldebaran is just 65 light-years away. It is a bloated star near the end of its life.
March 23: Runaways
The Orion Nebula, a stellar nursery, hangs below the hunter’s belt at nightfall. A binary star known as Iota Orionis is near the nebula. An encounter with another binary may have kicked one star from each system out into space, with the remaining stars forming a new binary.
March 24: First-Quarter Moon
The Moon is at first quarter today, exactly one-quarter of the way through its month-long cycle of phases. It lines up at a right angle to Earth and the Sun, so sunlight illuminates half of the lunar hemisphere that faces our way.
March 25: First Leap
A gazelle leaps past the Big Dipper. In ancient skylore it made three leaps, each marked by a pair of stars. Those that mark the first jump are Alula Borealis and Alula Australis. As night falls, they are almost due east, far to the right of the dipper.
March 26: Dog Stars
The stars Procyon and Sirius arc to the lower right of the Moon as night falls and wheel down the western sky later on. Sirius is the brightest star in the night sky. Procyon, which is much closer to the Moon, is in the top 10 as well.