Jimmy Westlake: Conquering the Hydra
April 15, 2013
What has nine heads, deadly breath, poisonous blood and stretches nearly one-third of the way around the whole sky? It's the dreaded sea serpent known as the Hydra, defeated by Hercules in the second of his twelve 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 multiple 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? Simple. Call on Hercules.
Hercules managed to destroy the Hydra by severing a head with his sword and then cauterizing 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 skewer the monster through the heart and kill it. All the while, Cancer the Crab was nipping at the strong man's toes as a distraction.
Hydra is not only the largest of the 88 constellations, but it also is 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 southwest to southeast. By 10 p.m. in mid-April, all of the sea serpent's body should be in view. You can locate Hydra's immortal head high in the southern sky, about halfway between the prominent spring stars Procyon and Regulus. Look for a small, distinctive pattern of five stars that curls around to form a letter "J." From his head, connect the star dots to the south and east along the snake's twisting body to locate Hydra's brightest star, Alphard, the "Solitary One," an orange-colored gem that sits alone in a rather blank patch of sky. It represents the heart of this monster. Continue connecting the star dots to the south and east, passing below 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.
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Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. His "Celestial News" column appears weekly in the Steamboat Today newspaper and his "Cosmic Moment" radio spots can be heard on local radio station KFMU. Check out Westlake's astrophotography website at http://www.jwestlake.com.