In the Sky This Month

With summer about to give way to fall, one of the main star patterns of the new season is climbing into prominence in the evening. The Great Square of Pegasus is in the east at nightfall. It’s tilted as it rises, so it looks like a diamond.

Cepheus the king passes high overhead tonight. The constellation’s five main stars form a pentagon. None of them is especially bright, though, so you probably need a star chart to find his majesty.

The brightest planet and star in the night sky are in good view at dawn now. The planet Venus is low in the east. It’s the “morning star.” The star Sirius twinkles far to the upper right of Venus. No other star in the night sky outshines it.

The Moon starts the week at the center of a beautiful morning lineup. It’s flanked by four points of light — two above, and two below. Venus, the “morning star,” is the bright point above the Moon, while the planet Mercury is the brightest point below.

Venus is shining as the brilliant “morning star.” Tomorrow, it will stand close to the lower left of the Moon at dawn. The star Regulus and the planets Mercury and Mars line up below them.

Mars is climbing into view in the dawn twilight. It’s not very bright, but it stands near some brighter bodies. Venus, the “morning star,” is high above it, with the star Regulus below Venus. The planet Mercury is below Regulus, with fainter Mars beside Mercury.

The planet Saturn is low in the south-southwest at nightfall. It looks like a bright star, with the true star Antares to the lower right. The Cassini spacecraft, which has been orbiting Saturn for 13 years, will end its mission tomorrow by plunging into Saturn’s atmosphere.

Andromeda, the princess, is in the east and northeast as the sky gets good and dark on September nights. It’s not especially bright, but you can find it by looking to the lower left of the more prominent Great Square of Pegasus.

The Moon is at last quarter at 1:25 a.m. CDT tomorrow, as the Sun illuminates half of the lunar hemisphere that faces us. This phase is known as last quarter because the Moon is three-quarters of the way through its month-long cycle of phases.

Aldebaran, the brightest star of Taurus, perches close to the Moon as they climb into view around midnight, and especially close at first light tomorrow. As seen from parts of the western U.S., the Moon will pass in front of Aldebaran, blocking its light.