In the Sky This Month

A traffic jam highlights the morning sky this month, as three planets line up near Regulus, the heart of Leo. The planets move through different configurations during the month, providing a different view each day. In the evening sky, some of the signature constellations of summer begin dropping from view, while some of the faint constellations of autumn climb skyward in the east and southeast.

September 24: Scutum

Scutum, a small, faint “shield” of stars, scoots across the southwestern sky on early autumn nights. It represents the coat of arms on the shield of John Sobieski, a 17th-century king of Poland and one of that country’s great heroes.

September 25: Moon and Companions

Antares, the bright heart of the scorpion, stands below the Moon as night falls, shining bright orange. The brighter planet Saturn is about the same distance to the left of the Moon.

September 26: Moon and Saturn

A pair of bright objects stands in the southwest this evening: the Moon and the planet Saturn. Saturn, the solar system’s second-largest planet, perches below the Moon, and looks like a bright star.

September 27: First-Quarter Moon

The Moon is at first quarter tonight. Sunlight illuminates exactly one-half of the lunar hemisphere that faces Earth. The sunlit portion of the Moon will continue to grow until the Moon is full on October 5, the date of the Harvest Moon.

September 28: Eagles

Several eagles soar across the sky tonight. The brightest is the star Vega, the swooping eagle, which is overhead at nightfall. Altair, the flying eagle, is in the southeast. The Eagle Nebula is a cloud of gas and dust that outlines a bird of prey with open wings.

September 29: Summer Triangle

Summer officially ended a week ago, but one of its most visible star patterns is still high overhead in the evening. The Summer Triangle consists of the bright stars Deneb, Vega, and Altair. The triangle is directly overhead about 8 p.m.

September 30: Double Double

Epsilon Lyrae stands quite close to Vega, one of the brightest stars in summer and autumn skies, which is high in the west at nightfall. Epsilon Lyrae consists of two pairs of stars. Each pair is tightly bound, with the two pairs quite far apart.