In the Sky This Month

For much of the country, September is a perfect time for some evening skywatching. The nights are longer and cooler but not yet frigid, and there’s plenty to look at. The Summer Triangle remains in good view high in the sky, while Scorpius and Sagittarius wheel across the southwest. In the east, Pegasus, Andromeda, and Perseus climb into view after sunset.

September 24: Moon in the Sea

The Moon is swimming through the Celestial Sea, a group of constellations with a watery theme. Tonight, the Moon is near the border between Aquarius, the water bearer; Pisces, the fishes; and Cetus, the whale or sea monster.

September 25: Arcturus

Look in the west as twilight fades this evening for one of the most commanding stars in the sky: Arcturus, in the constellation Bootes, the herdsman. It shines pale yellow-orange.

September 26: Chasing Dogs

Two “dog stars” chase across autumn’s pre-dawn sky. The brighter one is Sirius, in Canis Major, the big dog. The other is Procyon of Canis Minor, the little dog. Both are high in the sky at first light, with Procyon far to the upper left of Sirius.

September 27: Triangulum

Wedged into a cozy space between the well-known constellations Andromeda, Aries, and Perseus is tiny Triangulum, the triangle. Its three brightest stars form a long, thin wedge. It rises in the northeast in early evening.

September 28: Atoms for Peace

NGC 7252, the Atoms for Peace galaxy, is in Aquarius. The constellation is low in the southeast at nightfall, and scoots across the south during the night. NGC 7252 looks like electrons orbiting the nucleus of an atom.

September 29: Moon and Aldebaran

The Moon passes especially close to the bull’s bright orange “eye” tonight. Aldebaran is just an eyelash away from the Moon as they rise in late evening. The Moon will pass even closer to the star over the following hours.

September 30: NGC 5907

Draco is in the north and northwest as night falls, above the Big Dipper. One of the dragon’s highlights is NGC 5907, an unusually flat spiral galaxy that is well above the end of the dipper’s handle.