In the Sky This Month

The story of Jason and the Argonauts is told in the remains of the ancient constellation Argo Navis, which in modern times has been split into four constellations. Parts of these constellations pass low across the south on winter nights.

Many stars travel through our galaxy as members of large families. The closest of these star families is called the Hyades. It’s a collection of more than 100 stars, the brightest of which form the V-shaped face of Taurus, the bull.

Sirius, the Dog Star, is in the southeast this evening. It’s the night sky’s brightest star. It is led into the sky by Procyon, the little dog star, which is to the left of Sirius and a little higher.

The Moon was new on Tuesday as it passed between Earth and the Sun. Today the Moon has moved away from the Sun, but it still lines up in the Sun’s general direction. At that angle, the Moon form a thin crescent, which is low in the southwest at sunset.

Winter nights abound with some of the brightest stars in the sky: Rigel and Betelgeuse in Orion, Aldebaran in Taurus, Sirius in Canis Major (the big dog), and Procyon in Canis Minor (the little dog), to name but a few.

Few of the stars of Camelopardalis, the giraffe, are visible to the unaided eye. With binoculars, though, you can pick out several pretty sights. One is Kemble’s Cascade, a string of about 20 stars along the giraffe’s neck.

The star Epsilon Eridani is fairly faint, but under dark skies, it is visible to the unaided eye to the west of Orion. It stands well up in the south in early evening. The star is host to at least one planet, and perhaps more.

A few of the constellations of autumn still offer some nice evening sights. One example is Perseus, which stands high in the north in mid evening. One of its most beautiful sights is the Double Cluster — two star clusters that appear side by side.

If you look south two or three hours after sunset tonight, you’ll be gazing into Eridanus, the river, one of the largest of the 88 constellations. It’s long and winding, and not easy to see.

The brightest star of Eridanus, the celestial river, is at the river’s southern tip. In fact, the name Achernar means “river’s end.” It stands near Rigel, the bright star that marks the foot of Orion, which is in the southeast at nightfall.