With summer’s luminaries dropping from view, 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. The constellations that form the “celestial sea” — Capricornus, Aquarius, Pisces, and others with a watery theme — flow across the south during the night. The Milky Way arches high overhead during the evening, putting on a grand display from sites with dark skies.
This Week's Stargazing Tips
September 20: Moon and Regulus
Regulus, the brightest star of Leo, the lion, stands close to the left of the crescent Moon at dawn tomorrow. Regulus consists of at least four stars, although only one of them is bright enough to see with the eye alone.
September 21: Autumnal Equinox
Autumn arrives tomorrow at the autumnal equinox, the day on which the Sun crosses the equator heading south. Over the next three months the Sun will move even farther south, bringing shorter, cooler days to the northern hemisphere.
September 22: Autumnal Equinox
Under the astronomical calendar, today is the autumnal equinox. The Sun crosses the equator from north to south, marking the start of autumn in the northern hemisphere and spring in the southern hemisphere.
September 23: Cepheus
Cepheus, the king, rotates high across the north on autumn evenings. In that position, its brightest stars form a pattern that looks a bit like an ice cream cone.
September 24: Doomed Giant
A huge star in Canis Major, the big dog, is probably about to go “boom.” VY Canis Majoris is veiled by dust, so you need a telescope to see it, to the left of the dog’s hindquarters. It is likely to explode in the next million years or so.
September 25: Mars and Antares
Two orange pinpoints huddle close together in the southwest the next few evenings: the planet Mars and the star Antares. Tonight, Antares is to the lower left with Mars to the upper right. Mars will move up and over Antares over the next few nights.
September 26: Capricornus
Capricornus, the “gateway to heaven,” rolls low across the south this evening. It looks like a large triangle, with the longest side aligned east to west. Mythology says it is the gateway for human souls on their way to heaven.
Check last week's tips if you missed a day.