In the Sky This Month

The Big Dipper wheels around the North Star like the hour-hand of a giant clock, ticking off the hours of the night. Winter is an especially good time to watch it, because it’s in good view pretty much all night.

As befits his status as a hero, Perseus strides boldly across the sky tonight. He is high overhead at nightfall, crowning the sky with a couple of streamers of moderately bright stars.

The Moon reaches first-quarter at 10:47 p.m. CST. It lines up at a right angle to the line from Earth to the Sun, so sunlight illuminates half of the lunar hemisphere that faces our way.

A “bubble” that represents the dying breath of a Sun-like star is on the edge of Gemini, which is well up in the east at nightfall. Known as the Medusa Nebula, the bubble is about 1,500 light-years away, and it spans more than four light-years.

Wezen, the third-brightest star of Canis Major, is about to dump huge supplies of chemical elements into space – everything from carbon and oxygen to silicon and iron. It will expel enough material to make several stars as massive as the Sun.

The planet Saturn poses near the Moon the next couple of evenings. It looks like a bright golden star. It stands to the upper left of the Moon tonight, and a bit farther below the Moon tomorrow night.

In ancient Greece and Rome, Orion was known as a mighty hunter. But in ancient Egypt, the figure was even mightier. It represented Osiris, the god of the underworld. In fact, Osiris was thought to reside in the stars of Orion’s Belt.

Orion is in the east and southeast at nightfall. Bright orange Betelgeuse marks its left shoulder. Lambda Orionis, to the upper right of Betelgeuse, looks fainter, but it consists of two monster stars, one of which may be 200,000 times brighter than the Sun.

Betelgeuse, the bright shoulder of Orion, is a third of the way up in the east-southeast at nightfall, to the left of Orion’s Belt. Astronomers have recently detected a possible companion star that appears to be a little bigger and heavier than the Sun.

In “Star Trek,” the star 40 Eridani is home to the planet Vulcan. Astronomers haven’t found any planets orbiting the star, however. 40 Eridani is in the southeast at nightfall, far to the upper right of Orion’s Belt. Under dark skies, it is visible to the eye alone.