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In the Sky This Month

A new season opens up in the evening sky. Pegasus slides into view in the east shortly after night falls, marked by the Great Square, while the constellations of the “celestial sea”—Capricornus, Aquarius, Pisces, and others—flow across the south.

September 30: Moon and the Scorpion

Some of the bright stars of the scorpion line up near the Moon tonight. The brightest star, Antares, is quite close to the Moon. Acrab, in the scorpion’s head, is farther to the right of the Moon. Both stars are fated to blast themselves to bits as supernovae.

October 1: Disappearing Scorpius

Two of the constellations of summer bookend the Moon tonight. Sagittarius is to the left of the Moon at nightfall. Some of its bright stars form the shape of a teapot, with the Moon near the tip of the spout. Scorpius curls below and to the right of the Moon.

October 2: Almach

Almach, one of the brightest stars of the constellation Andromeda, is in the northeast as night falls and passes high overhead in the wee hours of the morning. A telescope reveals two stars, one of which is yellow orange, the other blue.

October 3: Watery Moon

The Moon is moving from one water constellation, Aquarius, to another, Capricornus. Many lunar features are associated with water, too. The dark patches that form the “man in the Moon” are known as seas or oceans. They are made of volcanic rock, not water.

October 4: Sending a Message

Vega, one of the brighter stars in the night sky, stands high overhead as twilight fades. It’s the leading light of Lyra, the harp. A team of scientists is pondering sending a message to possible alien life in that same constellation.

October 5: Moon and Saturn

Saturn stands close to the upper right of the Moon at nightfall. The planet looks like a bright star. It’s the second-largest planet in the solar system and it’s covered by bright clouds, which reflect most of the sunlight that strikes them.

October 6: Morning Mercury

Mercury just peeks over the eastern horizon the next few mornings. The planet is quite low in the sky 30 or 40 minutes before sunrise, so you need a clear horizon to find it. But it looks like a bright star, so it should hold in view as the twilight grows bolder.

First QuarterFirst September 3, 1:08 pm

Full MoonFull September 10, 4:59 am

Last quarterLast September 17, 4:52 pm

New MoonNew September 25, 4:55 pm

Times are U.S. Central Time.

Perigee September 7

Apogee September 19

The full Moon of September is the Fruit Moon or Green Corn Moon. This year it’s also the Harvest Moon.