In the Sky This Month

The constellation Canis Major, the big dog, is best known for its leading light: Sirius, the Dog Star, the brightest star in the night sky. It stands a third of the way up the southeastern sky at nightfall.

Three constellations in view this month are named for early machines: Sextans, Antlia, and Pyxis — the sextant, air pump, and magnetic compass. Sextans is low in the east in early evening, with Antlia and Pyxis climbing into the south and southeast.

Columba, the dove, scoots low across the south tonight, to the lower right of Sirius, the brightest star in the night sky. The constellation marks the opposite direction from the motion of the solar system as it orbits the center of the galaxy.

Mercury, the smallest of the solar system’s major planets, is hiding in the Sun’s glare. It lines up behind the Sun as seen from Earth. As it moves away from the Sun, it will climb into decent view in the early evening sky in a couple of weeks.

Beta Pictoris, a star in the constellation Pictor, is visible low in the south from the far-southern United States. The star is surrounded by a disk of debris which contains at least one planet. Astronomers have photographed the known planet.

The Moon is new today as it crosses the imaginary line between Earth and Sun. It is immersed in the Sun’s glow, so it’s not visible. It will return to view as a thin crescent in the western evening sky in a couple of days.

A partial solar eclipse will take place tomorrow, but it won’t be visible from the United States. The eclipse will sweep across Antarctica, the Southern Ocean, and parts of South America. At its peak, the Moon will cover about half of the Sun’s disk.

Every night as darkness falls, lonely Polaris, the pole star, pops into view in the north. Unlike the other stars, which move from night to night, Polaris remains in the same spot, marking the hub of the northern sky.

The Milky Way arcs high overhead this evening. It is anchored in the southeast by Sirius, the night sky’s brightest star. It climbs overhead to the “horns” of Taurus, then drops toward M-shaped Cassiopeia and the tail of the swan in the northwest.

A beautiful target for binoculars stands in the southeast this evening, well to the left of sparkling Sirius, the brightest star in the night sky. Messier 48 is a cluster of more than 100 stars, about 1,500 light-years away.