Jimmy Westlake: The eyes of the dragon
September 16, 2013
Steamboat Springs — Peering at us from out of the darkness on early fall evenings are the twinkling eyes of Draco, the Dragon. This millennia-old constellation represents Ladon, the dragon that guarded the golden apples of the Hesperides in Greek mythology. The two stars marking Draco's eyes are striking because they are nearly the same brightness and appear so close together in the sky, making them easy to spot.
Draco is one of several constellations in the sky that depict a creature killed by Hercules, the great strong man from mythology. Hercules was forced to pay penance for the murder of his wife and children by completing 12 nearly impossible tasks. These were the 12 labors of Hercules. All of this was a scheme to get rid of Hercules concocted by the jealous queen of the Greek gods, Hera.
In his 11th labor, Hercules was commanded to find the Garden of the Hesperides and bring back the golden apples that grew there. No big deal, except that the apples were guarded by a dragon with 100 eyes, half of which never slept. Hercules killed the dragon with a poisoned arrow and humbly presented the golden apples to Hera, who then immortalized the sacrificial dragon as the stars of our constellation Draco.
The Eyes of the Dragon, named Eltanin and Rastaban, are located high in the western sky at about 10 p.m. in late September, close to the dazzling white star Vega. Eltanin is Draco's brightest star. It is now 148 light years away but is moving toward us and in 1.5 million years will be only 28 light years away, replacing Sirius as the brightest star in our sky.
The other eye, Rastaban, is a yellow giant star that pumps out 900 times more energy than our sun. A planet orbiting Rastaban would need to be 30 times Earth's distance from the sun in order to bask in comfortable, Earth-like temperatures.
Near the end of Draco's tail is the star Thuban. Five thousand years ago, Thuban was located near our north celestial pole, like Polaris is for us today. The ancient Egyptians and builders of the Great Pyramid of Cheops aligned the pyramid's central passage such that their pole star, Thuban, was constantly visible from the bottom of the chamber.
The head of Draco the Dragon is circumpolar as seen from Northwest Colorado. This means that the eyes of the dragon are located so close to the north celestial pole that they never dip below our horizon. Could this be the origin of the legend that Ladon, the Dragon of the Hesperides, never slept? The Eyes of the Dragon always are watching.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. His “Celestial News” column appears weekly in the Steamboat Today, 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.