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In the Sky This Month

The Celestial Sea wheels into the east and southeast during September evenings. This group of constellations all relate to water. Capricornus, the sea goat; Aquarius, the water bearer; Piscis Austrinus, the southern fish; and Pisces, the fishes are in view as darkness falls. Cetus, the sea monster, and Eridanus, the river, follow behind them. They may share an aquatic theme because autumn was a rainy season in the ancient Mediterranean, where the constellations were named.

September 27: Fading Symbol

Scorpius, the scorpion, is quite low in the south and southwest as night falls. Its brightest star, Antares, is still easy to see. But the scorpion’s body, which stretches to the lower left of Antares, and its head, to the right of Antares, are harder to pick out.

September 28: Lacerta

Lacerta, the lizard, scurries high overhead on September evenings. It is between the outstretched wings of Cygnus, the swan, and W-shaped Cassiopeia. You need dark skies and a starchart to help you find this squiggle of five stars.

September 29: Algol

A star with a demonic reputation climbs the northeastern sky this evening. Algol represents the head of Medusa, a monster that’s part of the constellation Perseus. The star fades and brightens, which may have helped inspire its reputation.

September 30: The Coathanger

The Coathanger, a pattern of 10 stars that looks like an upside-down hanger, is one of the highlights of the faint constellation Vulpecula, the fox. It is a great target for binoculars.

October 1: Harvest Moon

The Harvest Moon lights up the sky tonight. The most common rule defines the Harvest Moon is the full Moon closest to the fall equinox. Most years, that places it in September. This year, though, October’s full Moon was closer to the equinox.

October 2: Bright Pairings

At nightfall, the planets Jupiter and Saturn are in the south. They look like a pair of bright eyes, with Jupiter far brighter than Saturn. And an hour later, the Moon and Mars climb into view. Mars looks like a brilliant orange star to the lower left of the Moon.

October 3: VV Cephei

A big, messy star system is at the center of Cepheus, the king, which is in the north-northeast at nightfall. VV Cephei consists of two giant stars. One is encircled by a disk of gas and dust. Every 20 years, the disk eclipses the other star for 21 months.

Full MoonFull Sept. 2, 12:22 am

Last quarterLast Sept. 10, 4:26 am

New MoonNew Sept. 17, 6:00 am

First QuarterFirst Sept. 23, 8:55 pm

Times are U.S. Central Time.

Apogee September 6

Perigee September 18

The full Moon of September is known as the Fruit Moon or Corn Moon.