Jimmy Westlake: Conquering Hydra
April 13, 2010
Steamboat Springs — What has nine heads, poisonous blood, deadly breath and stretches nearly one-third of the way across the whole sky? It's the dreaded sea serpent known as Hydra, defeated by Hercules in the second of his 12 labors and now forming the largest of our 88 constellations.
Hydra is one of the 48 original Greek constellations, passed down to us from centuries ago. It always has been associated with the legendary sea serpent that battled with Hercules in the swamps of Lerna. This beast had many heads that, when cut off, immediately would sprout back as one or more new heads. One head was even immortal and could not be cut off. How can you hope to defeat such a monster?
Hercules managed to destroy the Hydra by severing a head with his sword and then scorching the wound with a burning tree stump before new heads could sprout. He then buried the immortal head under a large boulder long enough to pierce the monster through the heart and kill it. All the while, Cancer the Crab (another nearby constellation) was nipping at the strong man's toes as a distraction.
Hydra is not only the largest of the 88 constellations, but it is also the longest, stretching more than 100 degrees across our southern sky on spring evenings.
To locate Hydra from stem to stern, you'll need to find a location away from the city lights with a clear view of the southern sky, from southeast to southwest. By 11 p.m. in early April, all of the sea serpent's body should be in view. You can locate Hydra's immortal head high in the southwest sky, not far below the bright planet Mars and the faint constellation of Cancer the Crab. Look for a small, distinctive pattern of five stars that curls around to form the letter "J."
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From his head, connect the star dots to the south and east along the snake's twisting body to locate Hydra's brightest star, an orange-colored gem that sits all alone in a rather blank patch of sky. This is Alphard, the "Solitary One," referring to its apparent isolation from other bright stars. It represents the heart of the monster. Continue connecting the star dots to the south and east, passing beneath the prominent kite-shaped star pattern of Corvus the Crow. The star marking the end of the serpent's tail is found about one hand span below Virgo's bright blue star Spica.
Once you've successfully located Hydra from head to tail, perhaps you'll feel the same satisfaction that Hercules must have felt when he, too, conquered this monster.
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 across the world. Check out Westlake's Web site at http://www.jwestlake.com.