Apair of prominent constellations heralds the short, hot nights of summer: Scorpius and Sagittarius. By the middle of August, the scorpion stands due south as night falls. Under an even modestly dark sky, you should easily make out its curving body, punctuated by the hook-shaped stinger just above the horizon. Sagittarius follows Scorpius across the sky. Its brightest stars form the outline of a teapot. Under a dark sky, “steam” appears to rise from the spout — the hazy band of the Milky Way, outlining the disk of our galactic home.
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In the Sky This Month
August 17: Dog Days
The Dog Days of summer are either in full swing or just wrapping up. That’s because there’s no definition for the dates of the Dog Days. All we can say for sure is that they got their name from Sirius, the Dog Star, the brightest star in the night sky.
August 18: Starburst
If you can find an especially dark skywatching site as night falls, you’ll see the Milky Way arcing from teapot-shaped Sagittarius in the south, through the swan high in the east, and over to W-shaped Cassiopeia in the northeast.
August 19: Great Square
The Great Square of Pegasus stands low in the eastern sky at nightfall. It spans a large region, and is marked by the bright stars Alpheratz, Scheat, Markab, and Algenib.
August 20: Merging Galaxies
Hercules is high in the western sky on August evenings. One of its most interesting features is NGC 6052, a pair of spiral galaxies in the process of merging. Through a telescope, the galaxies look like a pair of spiders locked in mortal combat.
August 21: Vega
Vega, one of the closest and brightest stars in the night sky, stands straight overhead as darkness falls and drops to the northwest during the night. The name Vega comes from an Arabic name that means the eagle.
August 22: Aquila
Aquila, the eagle, soars high across the sky tonight, partially immersed in the glow of the Milky Way. Look beginning about an hour after sunset, when Aquila and its brightest star, Altair, are halfway up the southeastern sky.
August 23: Moon and Aldebaran
Look for the face of the bull at dawn tomorrow, to the right of the Moon. The bright star close to the Moon is Aldebaran, the bull’s eye. It moves through the galaxy alone. The other stars in the V-shaped face are members of the Hyades star cluster.