The stars of autumn begin to push those of summer out of the way as the nights grow longer and cooler. Pegasus is in view in the east as night falls, with several related constellations following the flying horse into the sky over the next few hours.
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In the Sky This Month
September 1: Zenith
Two points of the Summer Triangle crown the sky tonight. Depending on your latitude, they can pass at or quite close to the zenith, the point directly overhead. Vega is up first, in early evening, followed by Deneb a couple of hours later.
September 2: Heartbeat Stars
Several “heartbeat” stars are in Cygnus. The swan’s brightest star, Deneb, is high in the east-northeast at nightfall. The heartbeat stars are binaries that follow elongated orbits. As a result, the systems brighten and dim in a way that resembles the pulse of a beating heart.
September 3: Moon and Jupiter
The Moon and the planet Jupiter put on a good show the next couple of nights. They climb into good view by about 11 or 11:30 p.m. Jupiter looks like a brilliant star near the Moon. Only the Moon and the planet Venus outshine it.
September 4: Labors
The western evening sky offers a figure that seems just right for Labor Day: Hercules, the strongman. In mythology, he had to labor not once, but 12 times. If you have a dark sky, look for Hercules high in the west after nightfall.
September 5: Moon and Aldebaran
Aldebaran, the bright orange eye of the bull, rises below the Moon late tonight, and follows the Moon across the sky. Aldebaran has puffed up, becoming a red giant. The Sun will enter that phase of life in several billion years.
September 6: Moon and El Nath
The two brightest stars of Taurus, the bull, flank the Moon late tonight. The brighter of the two, Aldebaran, is to the right of the Moon as they climb into good view, about 1 a.m. The second-brightest star, El Nath, is closer to the left or lower left of the Moon.
September 7: Busy System
The system 55 Cancri consists of two stars and at least five planets. None of the planets is a good home for life, however. The system is in Cancer, which is in the east at first light. The crab is easy to pick out because it spreads to the upper left of Venus, the Morning Star.
Last September 6, 5:21 pm
New September 14, 8:40 pm
First September 22, 2:32 pm
Full September 29, 4:58 am
Times are U.S. Central Time.
Apogee September 12
Perigee September 27
The full Moon of September is the Fruit Moon or Green Corn Moon. This year it’s also the Harvest Moon.