Jimmy Westlake: Have you seen the great dark horse?


Jimmy Westlake

Jimmy Westlake's Celestial News column appears monthly in the Steamboat Today.

Find more columns by Westlake here.

— This black stallion, disguised as dark nebulae, prances through the stars of the Milky Way about midway between Jupiter and the star Antares. During the dark of the moon, the Great Dark Horse can be glimpsed with the naked eye from rural skies.

As soon as night falls, the misty star clouds of the Milky Way arch across our summer sky from the northeast all the way to the south. The band of the Milky Way that we see from Earth is but a small part of our vast Milky Way Galaxy, a spiraling mass of more than 100-billion suns, and its star clouds are composed of millions of stars too distant and too numerous to distinguish as separate stars. If the sky is clear and the night is dark, you also can see a network of dark tendrils and filaments meandering through the bright star clouds of the Milky Way. These dark nebulae are made of interstellar dust that gathers in enormous clouds between the stars. The closest stars to us leave the band of the Milky Way and fill our sky with hundreds of points of light that form our familiar 88 constellations.

The dark of the moon in early August this year will allow us to see something truly wonderful, the illusive Great Dark Horse Nebula in the Milky Way. The Dark Horse is not made of stars like other constellations but is made from the absence of stars. He is a collection of dark nebulae that forms the silhouette of a black stallion, reared high on his hind legs, against the bright star clouds behind him.

You can spot the Great Dark Horse with your naked eye; in fact, optical aid renders the Dark Horse invisible. He is about as large as your fist held at arm's length and hides in the patch of sky between the fishhook pattern of Scorpius the Scorpion and the teapot pattern of Sagittarius the Archer. His prominent hindquarters, also known as the Pipe Nebula, stand out in sharp contrast against the dense star clouds toward the galactic center. Look due south about 10 p.m. in early August, roughly midway between the brilliant planet Jupiter and the bright star Antares and about one-third of the way up in the sky. There, you should spy the shadowy figure of the Great Dark Horse.

If you don't spot him at first, keep looking as if at an ink blot test. Once you see him, you'll wonder how you ever overlooked something so obvious. He only comes out during the dark of the moon in late summer, so now is your chance to see the sky's best-known dark constellation, the Great Dark Horse.

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 Web sites of CNN.com, NASA's "Astronomy Picture of the Day" Web site, Spaceweather.com, Space.com, Discover.com, MSNBC.com, NationalGeographic.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines. His "Celestial News" article appears weekly in the Steamboat Pilot & Today. His "Cosmic Moment" radio spots can be heard on local radio station KFMU. Also, check out Jimmy's Web site at www.jwestlake.com.


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