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HERCULES
The Strongman
Hercules - Celestial Atlas by Alexander Jamieson - 1822
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To the Greeks he was Heracles, to the Romans, Hercules. He was the great grandson of the hero Perseus. The son of Zeus (Jupiter) and the mortal woman Alcamene, Hercules displayed extraordinary strength from an early age, and played a part in many ancient legends, most notably the expedition of Jason and the Argonauts, and the famous Twelve Labors of Hercules.
Hera, the wife of Zeus, hated Hercules, the fruit of her husband's infidelity, and caused him to go insane and murder his entire family. The twelve labors were imposed on Hercules as a penance for his crime, and two of the strong man's labors have constellations of their own in the sky. The first labor of Hercules was the killing of the Nemean Lion, represented by the constellation Leo. The second labor was the killing of the many headed sea monster, the Lernaean Hydra, represented by the constellation Hydra. The constellation Taurus is sometimes connected with the seventh labor of Hercules, the capture of the Creton Bull, although Taurus is more widely associated with the myth of Zeus and the maiden Europa.
When Hercules completed all twelve labors, all was forgiven. Even Hera was impressed, and rewarded him by offering him her daughter, Hebe, as his bride. His father, Zeus, was so impressed he put Hercules and two of his labors up among the stars for all to see.
Hercules is one of the oldest known constellations, known as the kneeling one, or the man on his knees, since the time of Plato and Hipparchus.
To find Hercules, start with the brilliant star Vega, in the constellation Lyra. Shift your gaze slightly to the west, and you should have no problem seeing the square of stars that make up the asterism known as the Keystone of Hercules. The figure of the strongman is always depicted on his knees, upside down in the sky.
The alpha star in Hercules is not the brightest star in the constellation, but designated alpha because it represents the head of the figure. It is named Ras Algethi, from the Arabic for the head of the kneeler.
There are fifteen stars in Hercules that are known to support planetary systems. Although all of these stars are beyond naked eye visibility, seven of them support planets significantly smaller than Jupiter, increasing the possibility of Earth size planets, and the possibility of extraterrestrial life. The star with the smallest, most Earth-like planet to date is HD 156668, 78 light years away, with a planet 100 times smaller than Jupiter. For more information on extrasolar planets visit NASA's Planet Quest.
The constellation contains the largest and brightest globular star cluster in the northern sky, M13. You can actually see M13 with your naked eye, but it is much more impressive with binoculars. And if you're lucky enough to have a telescope handy, M13 is one of the more spectacular sights in the night sky.
Historically referred to as planetary nebulae, these cosmic phenomena have nothing to do with planets. The two notable nebulae in Hercules are shells of expanding gas generated by stars that have used up their nuclear fuel, and are shedding their outer layers, on their way to becoming small, dense white dwarfs. NGC 6210 is 6,500 light years away. At a magnitude of 9.5, it is discernible in a backyard telescope as a small, blue-green disk. Through the eyes of Hubble, its true nature is revealed.
At a distance of 7000 light years, and with a magnitude of 10.7, the planetary nebula IC 4593 is a little harder to find in a small scope. Once again, we turn to the large space telescopes to see its real glory.
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