Jimmy Westlake: Canis Minor – playing second fiddle
March 25, 2007
It’s tough to be always standing in someone else’s limelight and never feel appreciated for who you are. I imagine that’s how Canis Minor, the constellation of the Little Dog, must feel running alongside his larger, better-known companion, Canis Major, the Big Dog. Canis Major has its flashy alpha star Sirius outshining all of the other stars in the area, even Canis Minor’s very bright star Procyon. So, I’m dedicating this Celestial News to all the “little dogs” out there, and Canis Minor in particular.
Canis Minor is a puny little pup, indeed, ranking 71st in size of all the 88 constellations. And, truth be known, the three main stars of this diminutive little star pattern look nothing at all like a dog : at least, not the four-legged variety. One might imagine the outline of a hotdog in these stars, but that’s about it. The fact is, were it not for Canis Minor’s alpha star, Procyon, this would be an easy constellation to overlook and dismiss as unimportant.
Ah, but Procyon more than makes up for the Little Dog’s meager size. Procyon is the eighth brightest star in the sky and the fifteenth closest star system to Earth at a distance of just more than 11 light years. Why, that’s right in our cosmic backyard!
Procyon is accompanied in space by a white dwarf companion, called Procyon B, the collapsed core of a once giant star that has crushed itself with gravity into a star the size of the Earth. Squeezing that much matter into such a tiny ball creates an incredibly dense object. A teaspoonful of Procyon B would weigh about 15 tons!
But, none of this really makes Canis Minor unique. Canis Major’s bright star Sirius is both brighter and closer to us than Procyon, and it, too, has a white dwarf companion, Sirius B. Sometimes, little dogs just have to be satisfied with what they can do best, and what this little dog can do better than anyone else is announce the arrival of his big companion. The ancient Greeks named this star Procyon because it means “before the Dog.” You see, Procyon rises in the eastern sky just minutes before the Dog Star, Sirius, rises, and then it precedes Sirius as they both prance westward across the sky.
So, take heart, Canis Minor, and be proud of doing your job well, night after night!
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Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. He is an avid astronomer whose photographs and articles have been published on the websites of CNN.com, NASA’s “Astronomy Picture of the Day,” Spaceweather.com, Space.com, Discover.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines. His “Celestial News” article appears weekly in the local Steamboat Pilot newspaper. He also records a radio spot called the “Cosmic Moment” for the local radio station “The Range” at 107.3 FM.