In the Sky This Month

Mars is stationary today, appearing to stand still against the background of stars, a result of the angle and relative motions of Mars and Earth in their orbits. After today, the planet will resume its normal eastward motion.

The star cluster Messier 41 trots along with the Dog Star, Sirius, the brightest star in the night sky. They stand due south about 9 p.m., with the cluster directly below Sirius. Under dark skies, M42 is just visible to the eye alone as a small, hazy patch of light.

A bright star in Cassiopeia is nearing the end of its life, so it is beginning to puff up like a giant balloon. Beta Cassiopeia is in the northwest this evening, at the bottom of a sideways letter W formed by some of the constellation’s leading lights.

Some of the brightest stars in the night sky form the Winter Circle, a jewel-studded cosmic necklace that fills much of the southern sky. Look for it as the sky gets nice and dark. The circle’s hub is bright orange Betelgeuse, in Orion the hunter.

Antares, the heart of the scorpion, stands just a whisker away from the Moon early tomorrow. The supergiant star has surrounded itself with giant clumps of dust. That makes it tough for astronomers to distinguish the star’s surface from the material around it.

Two bright orange stars pass high across the south this evening: Betelgeuse, at the shoulder of Orion the hunter; and Aldebaran, the eye of the bull, well to its right.

The dying star NGC 3242 has surrounded itself with a giant bubble of gas and dust. It’s called the Ghost of Jupiter Nebula for its resemblance to the giant planet. It climbs into view, in the southeast, by 9 p.m. Under dark skies it’s visible through binoculars.

Hydra, the water snake, is the largest and longest constellation. Its head is in the east in early evening, but its tail doesn’t clear the horizon until hours later. Only one of its stars is easily visible. You need dark skies to see any of the others.

The Moon has an especially close companion at dawn tomorrow: Spica, the brightest star of Virgo. Depending on your location, they might be separated by as little as the width of a pencil held at arm’s length. From some parts of the world, the Moon will cover the star.

One of the meekest constellations wheels across the south on February nights. Caelum, the chisel, is due south in early evening. It sits atop the horizon for those at the middle latitudes of the United States, and a little higher for those farther south.