In the Sky This Month

Some of the big constellations of autumn begin to push their way into the evening sky this month. Pegasus, the flying horse, is well up in the east at nightfall by month’s end, with Andromeda, the princess, to its left. Under especially dark skies, you should be able to pick out M31, the Andromeda galaxy. Venus, the Evening Star, inches higher in the western sky at sunset. And Mars begins to eke away from Antares and Saturn, although they remain fairly close throughout the month.

September 25: Triangulum

Tiny Triangulum, the triangle, wedges between the prominent constellations Andromeda and Aries. Its three brightest stars form an isosceles triangle, which looks like a long wedge. Triangulum is low in the east-northeast at nightfall.

September 26: Moon and Regulus

The Moon cozies up to Regulus, the brightest star of Leo, the lion, in the wee hours of tomorrow morning. They are well up in the east at first light, with Regulus close to the lower left of the Moon.

September 27: Moon and Mercury

Mercury lurks quite low in the east about 45 minutes before sunrise. It looks like a fairly bright star, but you need a clear horizon to see it. It will stand to the lower left of the Moon tomorrow, and just a whisker above the Moon on Thursday.

September 28: The Milky Way

The next few evenings offer a great chance to see the Milky Way, the hazy band of light that outlines the disk of our home galaxy. It arcs high across the sky at nightfall, and there’s no Moon around to spoil the show.

September 29: Messier 2

Some of the oldest stars in the galaxy congregate in the globular cluster M2. It is in the southeast at nightfall and wheels high across the south later on. Through binoculars, it looks like a fuzzy patch of light in the northwestern corner of Aquarius.

September 30: Old Clusters

A pair of globular star clusters is in the southeast at nightfall. M15 is highest in the sky, to the upper right of the Great Square of Pegasus. M30 is far below it, in Capricornus. Through binoculars, each looks like a fuzzy star.

October 1: Aquarius

The faint constellation Aquarius is low in the southeast at nightfall on these early autumn nights. Its stars represent a man or boy pouring water from a vase. In Greek mythology, he was the water bearer to the gods.