This is a busy skywatching month, with a partial lunar eclipse on the night of the Harvest Moon, a morning appearance by Mercury, and close encounters between the Moon and all five planets that are easily visible to the unaided eye. The constellations of autumn climb to prominence, while some of the last of the summer constellations disappear in the evening wilight.
The full Moon of September is the Fruit Moon or Green Corn Moon. This year it’s also the Harvest Moon.
Apogee September 5
Perigee September 18
Moon phases are Central Time
The Moon has a lot going on tonight. It’s the best-known full Moon of the year, the Harvest Moon. It will stage a minor eclipse that will be visible across almost all of the United States. And the bright planet Saturn will stand close to the Moon all night.
The planet Saturn lurks close to the Moon tonight. Saturn looks like a bright star. It will be close to the right of the Moon as night falls, and much closer at first light. From western parts of the country, the Moon will pass in front of Saturn, blocking it from view.
The constellation Cetus, the whale or the sea monster, is just moving into the evening sky. It clears the eastern horizon before midnight and swims into the southwest by daybreak.
For centuries, the star Alpheratz was shared by Pegasus the flying horse, and Andromeda the princess. It was his navel, and her head. It was the brightest member of both constellations. A century ago, however, it was assigned to Andromeda.
Lacerta, the lizard, is in the east-northeast at nightfall, to the upper left of the Great Square of Pegasus. It passes high overhead around midnight. Its stars are all so faint that you need fairly dark skies to see any of them.
The curving body of Scorpius, the scorpion, and the teapot shape of Sagittarius hunker low in the south and southwest at nightfall. Cygnus, the swan, soars high overhead. And W-shaped Cassiopeia is about a third of the way up the northeastern sky.
If you have clear, very dark skies before dawn over the next few mornings, look toward the eastern horizon for a ghostly pyramid of light, called zodiacal light. It is sunlight reflecting off of tiny grains of dust scattered throughout our solar system.
The Moon is at first quarter tonight. It lines up at a right angle to the line between Earth and the Sun, so the Sun illuminates half of the lunar hemisphere that faces our way.
Antares, the brightest star of the scorpion, stands near the Moon the next couple of evenings. Tonight, it is close to the upper left of the Moon at nightfall. It will be about the same distance to the right of the Moon tomorrow night.
With summer almost ready to give way to fall, one of the signature star patterns of the new season is climbing higher into the evening sky. The Great Square of Pegasus is in the east at nightfall. It’s tilted as it rises, so it looks more like a diamond than a square.
