In the Sky This Month

Look for the twin stars of Gemini near the Moon not long after nightfall. Castor is to the left of the Moon, with brighter Pollux to the Moon’s lower left. Bright orange Mars rises well below them.

Procyon, the brightest star of the little dog, climbs into view, due east, by about 9 p.m. That’s just before Sirius, the Dog Star, which rises to the lower right of Procyon. The name Procyon means “before the dog,” indicating that it leads the Dog Star across the sky.

This is a great night for werewolves and other lunaphiles in the northern hemisphere because it’s the night of the Long-Night Moon. It is the full Moon that’s in view longer than any other full Moon of the year.

Friday the 13th brings a bit of bad luck for skywatchers. The Geminid meteor shower is at its peak, and it’s generally one of the year’s best, with more than 100 meteors per hour. But the Moon is almost full, so it will overpower all but the brightest meteors.

Look to the northwest after nightfall this evening for the Northern Cross, the same stars that outline Cygnus, the swan. As it begins to set, a few hours after sunset, the cross stands upright, as though it were anchored to the horizon.

Gamma Cephei is a future North Star. A thousand years from now, it will be closer to the north celestial pole than Polaris, the current North Star. You can find it standing directly above Polaris at nightfall at this time of year.

Vulpecula, the fox, is well up in the west as night falls. The constellation is between the stars Deneb and Altair, the two points that form the top side of the bright Summer Triangle.

From the far-southern U.S., the star Beta Pictoris just climbs into view around midnight. It is low in the south, to the upper right of Canopus, the second-brightest star in the night sky. Beta Pictoris has two known planets plus the ingredients for making more planets.

The Moon is at first quarter this morning, one-quarter of the way through its month-long cycle of phases. Sunlight illuminates half of the lunar hemisphere that faces our way.

The Moon barrels toward Saturn tonight. The planet looks like a bright star, to the upper left of the Moon at dusk. As they drop lower, the gap will close. From most of the country they will be separated by the width of one or two fingers held at arm’s length.