But through telescopes it becomes a sight to behold. Binoculars will show it as a pale, colorless glow with a diameter as much as half that of the moon. With a total light equivalent of about a sixth-magnitude star, it can be seen with the unaided eye in a very dark sky, as it was by Edmond Halley, who discovered this cluster in 1714.Īt a distance of roughly 22,000 light years, M13 is among the nearest globulars scientists believe that this great swarm contains at least several hundred thousand stars. It is within the Keystone, about two-thirds of the way from the butterfly's head along the western edge of the northern wing. The object that always draws the most attention in Hercules and is regarded as a showpiece for Northern Hemisphere observers is M13, the Great Globular Cluster in Hercules. Interestingly, in our current evening sky, as Hercules stands triumphantly at the top of the heavens, the tail of the constellation Hydra can be seen slithering below the southwest horizon and hurrying out of sight. But Hercules emerged victorious by having his nephew, Iolaus, burn the stump of each severed neck, preventing new heads from sprouting. Infuriated with the crab's less-than-heroic fate, Juno banished this hapless creature to the heavens as one of the most inconspicuous of the traditional constellations.Īs for the Hydra, each time Hercules lopped off one head, two others grew in its place. Her crustacean arrived just at that moment that Hercules was busy slaying the multiheaded Hydra, one of his 12 assigned superhuman "labors."īut Cancer's bite was no more than a mere annoyance to our hero, who abruptly crushed the attacker under his heel. There is actually a connection between Hercules and two other constellations, the nine-headed serpentine water monster known as the Lernean Hydra, and a much smaller creeping sea creature.Ī jealous Juno summoned a crab ( Cancer) to fatally bite Hercules. The great Roman author, statesman and philosopher Lucius Annaeus Seneca (4 BC-AD 65) relates in verse some of the leading Hercules legends in "Hercules Furens" ("Mad Hercules"), including a diatribe by Juno against Hercules - her husband's (Jupiter's) demigod son by another woman, the mortal Alcmene. When astronomical bodies are given mythological names in modern times, the Latin version has generally been preferred. Thus, Zeus became Jupiter Hera, Juno Ares, Mars and so forth. Many Greek gods, heroes, heroines, and other legendary personalities were adopted by the Romans, who identified them with characters of their own. We call him Hercules in keeping with the tradition of using Latin names for the constellations. Hercules was known in Greek culture as Heracles, and the extensive legends surrounding him are among the best known of Greek mythology. Baker traced out Hercules as "a figure of six stars that outlines a butterfly with outstretched wings." This figure also somewhat resembles the letter "H," which of course is also the initial for Hercules. Meanwhile, in his book "Introducing the Constellations" (opens in new tab) (Viking Press, 1937), astronomer Robert H. Meanwhile, the star Ras Algethi that the ancients considered the hero's head marks Hercules' left foot. Rey reimagined this group of stars according to its current orientation as "a man swinging a club," he writes, "Hercules' favorite weapon." In Rey's version, a keystone-shaped quadrilateral - which the ancients envisioned as his waist and hips - ends up as Hercules' head. In other words, Hercules is now standing on his head! Hercules' brightest star is third-magnitude Ras Algethi, which is Arabic for "Head of the Kneeler." And indeed, in the sky Hercules was portrayed posturing on one knee, with Ras Algethi, a red supergiant star, marking his head.īut over the past 5,000 years, the wobbling of the Earth's axis (called "precession") has caused the position of the stars to shift in such a manner so that today Hercules appears to be performing acrobatics, with his head passing well south of the zenith. Mesopotamian skywatchers in 3000 BC saw Hercules standing upright high in the northern sky during the summer. famous for his strength, but as a constellation he is rather weak, without bright stars." Rey perhaps said it best when he noted that "Hercules was. In his book "Find the Constellations" (opens in new tab) (Houghton Mifflin Co., 2008), author H.A.
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