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In the Sky This Month

October offers some of the best skywatching conditions of the year. The nights are getting longer, while the weather is cooler but not frigid. The evening sky offers such treats as Andromeda and her famous galaxy, M31, as well as several other constellations associated with her mythological story. Other highlights include the two most prominent star clusters in the sky, the dipper-shaped Pleiades and nearby V-shaped Hyades, both in Taurus.

October 22: Pherkad

The star Pherkad, which forms the lower outer corner of the Little Dipper’s bowl, is much bigger, brighter, and heavier than the Sun. Over a period of a few hours, though, its brightness varies by a few percent, and astronomers aren’t sure why.

October 23: Moon and Saturn

Look for the planet Saturn near the crescent Moon early this evening. It looks like a bright star to the left of the Moon as twilight fades away. They set about three hours after the Sun.

October 24: More Moon and Saturn

Saturn, the solar system’s second-largest planet, huddles to the lower right of the Moon at nightfall this evening. Saturn has the largest ring system of any of the Sun’s planets, and the second-largest known retinue of moons.

October 25: Drawing Stars

Andromeda, the princess, is in the east and northeast at nightfall. It’s faint, though, so you need dark skies to see it. Andromeda is associated with several other constellations that share a common story.

October 26: Blue Snowball

One of the treasures of the constellation Andromeda, which is low in the east and northeast at nightfall, is the Blue Snowball Nebula, a bubble of gas expelled by a dying star. The nebula is at the right edge of the constellation, above the Great Square of Pegasus.

October 27: First-Quarter Moon

The Moon is at first quarter today. It rises in early afternoon and sets around midnight. At first quarter, sunlight illuminates exactly half of the lunar hemisphere that faces Earth, so it looks as though someone sliced the Moon down the middle.

October 28: Moon Watching

A beautiful Moon slides across the southwestern sky this evening, in Capricornus. It is a day past first quarter, so the Sun illuminates more than half of the lunar hemisphere that faces our way. The Moon sets about 1 or 2 a.m.

Current moon phase

Full MoonFull Oct. 5, 1:40 pm

Last quarterLast Oct. 12, 7:25 am

New MoonNew Oct. 19, 2:12 pm

First QuarterFirst Oct. 27, 5:22 pm

Times are U.S. Central Time.

Perigee October 9

Apogee October 24

The full Moon of October is known as the Harvest Moon or Dying Grass Moon.