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Last Week's Stargazing Tips

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 24: Autumn Star

The best sign in the night sky that fall has arrived is the appearance of the “autumn star.” It’s the only bright star that puts in its best showing during the nights of autumn: Fomalhaut, the leading light of Piscis Austrinus, the southern fish.

September 23: Last-Quarter Moon

The Moon reaches last quarter today. Half of the side that faces Earth is bathed in sunlight, while the other half is in darkness. When the Moon is at last quarter it is leading Earth in our planet’s orbit around the Sun.

September 22: Autumn Skies

The Sun changes hemispheres today. It crosses the equator from north to south, a moment known as the equinox. That ushers in autumn here in the northern hemisphere, and spring in the south.

September 21: Mu Cephei

The reddest star in northern skies stands high overhead during the evening hours. Its official designation is Mu Cephei, but it is also known as the Garnet Star. It is a red supergiant, which means it is much larger and cooler than the Sun.

September 20: Moon and Aldebaran

Aldebaran, the bright orange eye of Taurus, the bull, rises to the lower left of the Moon before midnight, and stands closer to the Moon at first light tomorrow.

September 19: Vela X-1

Enif, the star at the nose of Pegasus, the flying horse, is in the east at nightfall, to the upper right of the Great Square of Pegasus. The star is about 670 light-years away, so the light we see from it tonight actually left the star in the 1340s.