Jimmy Westlake: Stargazing? Start with the Winter Hexagon
December 22, 2014
Steamboat Springs — The Winter Hexagon spotlights eight of the 20 brightest stars in earthly skies and makes a superb starting point for backyard astronomers trying to learn their way around the winter sky.
The misty band of the Milky Way slices right through the heart of the Hexagon, and it is flanked by two of the sky’s most beautiful naked-eye star clusters. The dipper-shaped Pleiades star cluster leads the way as the Winter Hexagon marches westward, and the Praesepe cluster, or the Manger, brings up the rear.
You can locate the first star in the Winter Hexagon by extending a line through the familiar three stars of Orion's belt to the left. The flashy star you come to is Sirius, the Dog Star, the brightest star in the heavens and the closest of the seven stars in the Winter Hexagon, at a distance of only nine light-years.
From Sirius, shoot a line to the upper right and find the bright icy-blue star Rigel that marks the foot of Orion the Hunter. Rigel is located 900 light-years away, 100 times farther away from us than Sirius.
To the upper right of Rigel is the orange giant star Aldebaran, marking the eye of Taurus the Bull. Aldebaran is 68 light-years away. Its name means "the follower" because it closely follows the Pleiades star cluster as it glides across the sky.
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Continue from Aldebaran by extending a line nearly overhead to the second brightest star in the Winter Hexagon, Capella, in Auriga, the Charioteer. Capella is 45 light-years away, and although it looks like a single star to the unaided eye, astronomers have discovered that it is composed of the light from four different stars.
Dropping down from Capella toward the eastern horizon will lead you to a prominent pair of bright stars, the Gemini Twins, Castor and Pollux. Pollux, the brighter of the twins, lies 35 light-years away while Castor shines from a distance of 52 light-years.
From the Gemini Twins, the Hexagon continues southeast to the star Procyon. This star's name means "before the dog," and it is aptly named because it rises in our sky just minutes before the Dog Star, Sirius, appears. Procyon, like Sirius, is a nearby star, only 11 light-years away.
Close the Winter Hexagon by shooting a line from Procyon back to Sirius, where we started.
As if having seven of the sky's brightest stars in one spot weren't enough, we easily can add an eighth.
Near the center of the Winter Circle is the red supergiant star Betelgeuse that marks the shoulder of Orion. Betelgeuse is very far from us, at a distance of 520 light-years, and is so large that, if placed in the center of our solar system, it would devour all of the planets out to Jupiter.
Once you've located the eight stars of the Winter Hexagon, compare their colors and see if you can rank them from coolest (reddest) to hottest (bluest). Then pat yourself on the back for a job well done.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. Check out Westlake’s new "2015 Cosmic Calendar" of sky events on his website at http://www.jwestlake.com. It features 12 of his best astrophotographs and a day-by day listing of cool celestial events that you and your family can enjoy watching in 2015.