By Dennis Mammana- If you haven’t been stargazing for a few months, you might be surprised when you step outdoors in January and view the dark early-evening sky.
Astronomers often refer to this sky as the most brilliant of the year. What we mean, of course, is that the stars appear much more dazzling during the Northern Hemisphere winter than any other season of the year.
Many folks tend to think that the stars shine so brilliantly at this time of year because the weather is so cold and that somehow makes them appear bright and crisp, but there’s actually a more fundamental reason for their brilliance: The winter night sky contains more bright stars than any other season.
It really is as simple as that.
Each season of the year features its own collection of stars and constellations.
The springtime and autumn skies contain relatively few bright stars, and the summertime sky features a few, as well as magnificent band of the Milky Way arching overhead. But the winter sky … oh, man, it is something else!
Just a few hours after dark during January, stargazers can find eight of the 25 brightest stars. The most dazzling, of course, is Sirius — the main star in Canis Major, the great dog. You can now find this sparkling gem low in the southeastern sky shortly after dark. It may appear to twinkle wildly as it rises over the horizon; its low elevation means its light must pass through a great deal of turbulent air on its way to our eyes.
Sirius is the most brilliant star in all the heavens (except, of course, for the sun). It outshines No. 2 — Capella in the constellation Auriga, the charioteer — by more than four times. You’ll easily spot Capella high in the northeastern sky after dark this month. It is the brightest star in a pentagon-shaped grouping that is much easier to trace than a charioteer.
Following Capella are, in order of decreasing brightness, Rigel (the southwestern corner of Orion, the hunter), Procyon (in Canis Minor, the lesser dog), the reddish Betelgeuse (the northeasternmost corner of Orion), Aldebaran (the brightest in Taurus, the bull), Pollux (in Gemini, the twins) and Castor (also in Gemini).
If seeing so many bright stars at once isn’t impressive enough for you, just wait until mid-month. You’ll have another brilliant beacon to add to the collection, one that’s considerably brighter than all these stellar gems combined. I’m referring, of course, to the moon.
The disadvantage of the moon’s return to the evening sky is that its brilliant light will decrease the contrast of all the stars against the dark night sky. The advantage of this collection of celestial beacons is that one doesn’t need to venture far off into the wilderness to see them. Even urban stargazers can easily enjoy the display right from home.
If, however, you decide to travel to a dark-sky site for your stargazing this month, you’ll need to bundle up and take some warm liquids with you. I promise this extra effort will be rewarded by the glittering stars that make up this magnificent wintertime night sky.