In the Sky This Month

One of the most beautiful galaxies is M51, also known as the Whirlpool because of its well-defined spiral arms. A small companion galaxy appears at the tip of one arm. It is in the northwest this evening, near the end of the Big Dipper’s handle.

The Moon will be “new” tonight as it crosses the imaginary line between Earth and the Sun, beginning a new cycle of phases. It will be lost in the Sun’s intense glare, but will return to view in a couple of days as a thin crescent in the west shortly after sunset.

Messier 22, a cluster that is about 10,000 light-years away, contains hundreds of thousands of stars, so it’s an easy target for binoculars. It’s in the south at nightfall, above the “lid” of the teapot formed by some of the brightest stars of Sagittarius.

M8, the Lagoon Nebula, is in the southern sky on August nights, above the “spout” of the teapot formed by the brightest stars of Sagittarius. Under especially dark skies, the birthplace of new stars is visible to the unaided eye as a faint smudge of light.

The center of the Milky Way galaxy is in Sagittarius, which rolls low across the southern sky on summer nights. Its bright stars form the outline of a teapot. The galactic center is above the spout of the teapot, immersed in the faint “steam” of the Milky Way.

Venus reigns as the brilliant “morning star.” The planet will stand quite close to the crescent Moon at dawn tomorrow, and farther to the upper right of the Moon on Sunday.

The star Sadr connects the body and wings of Cygnus, the swan, which soars high overhead on August nights. Sadr is a supergiant star. It’s at least a dozen times the mass of the Sun, 150 times wider than the Sun, and more than 30,000 times brighter.

Aldebaran, the bright “eye” of Taurus, the bull, is close to the Moon in the wee hours of tomorrow morning. Several faint stars appear quite close to Aldebaran, but most of them are unrelated — they just happen to line up in the same direction.

The Moon reaches last quarter at 11:45 a.m. CDT. Sunlight will illuminate half of the lunar hemisphere that faces Earth. The illuminated portion of the Moon will grow smaller over the next week as the Moon moves toward the Sun in our sky.

Venus is stretching its legs right now. The “morning star” stands farthest from the Sun over the next few days. It climbs into view about three hours before sunrise and is more than a third of the way up the eastern sky by the time it fades from view.