Hercules The Constellation

Check out the Great Hercules cluster of stars

If you look to the east at night with a telescope this week, you may see a bright cluster of stars with a powerful name and a discovery story that dates back to the 18th century.

The cluster is an especially beautiful Messier object known as the great globular cluster M13, in the constellation Hercules, which stands high in the eastern sky at dusk this week. Because of its location , the cluster is sometimes known as the Globular Cluster of Hercules. The sky map shows where the cluster appears in relation to other constellations.

Famous star clusters and glowing cosmic nebulas are often denoted by names that begin with the letter M, such as M42 (the Orion nebula) and M31 (the Andromeda galaxy). These objects are part of the storied Messier catalog, created by 18th-century comet observer Charles Messier (1730-1817). 

Find the Keystone To locate Messier 13 , look toward the four stars known as the "Keystone," which supposedly forms the body of Hercules.  A keystone is the stone atop an arch, and is narrower at one end. The keystone of Hercules is composed of the stars Eta, Pi, Epsilon, and Zeta Herculis.  It's an asterism, which is defined as a distinctive grouping of stars forming part of the recognized constellation outlines, or lying within its boundaries.

Ranging in size from sprawling naked-eye figures to minute stellar settings, asterisms are found in every quarter of the sky and at all seasons of the year.  The larger asterisms – ones like the Big Dipper in Ursa Major and the Great Square of Pegasus – are often better known than their host constellations.

It's between the two western stars of the keystone that we can find the Great Globular Cluster of Hercules.  It's about a third of the way along a line drawn from the stars Eta to Zeta.

Actually, it was not Messier, but Edmund Halley (of comet fame), who first mentioned this cluster in 1715, having discovered it the previous year: "This is but a little Patch," he wrote, "but it shows itself to the naked Eye, when the Sky is serene and the Moon absent."

USM Southworth Planetarium · [DA June 9, 2011] The Kneeling One

The most surprising aspect of the Hercules constellation is its faintness. One would think that the constellation-crafting gods would have bestowed a brighter stellar arrangement onto one of mythology’s most illustrious figures. After all, Zeus and his lot generally reserved the dim star patterns for either those characters whose accomplishments were under whelming (e.g. Cancer the Crab, whose principal achievement was being stepped on by Hercules) or who were of weak nature (e.g. the henpecked and spineless King Cepheus.) For these miserable characters, faint constellation depiction was more ignominious than honorable. Those familiar with Hercules, however, know that his accomplishments were both impressive and plentiful. Moreover, he was hardly weak either physically or mentally, apart, of course, from that insanity spell that his nemesis Hera cast onto him.

And, if we’re to discuss Hercules’ contributions, we can begin with this insanity curse, for under it’s influence, Hercules slaughtered his wife and children. After the murders, Hercules recovered his senses and tried to commit suicide at once. His friend and emulator Theseus intervened, and he persuaded the horrified Hercules to consult the Delphic Oracle for guidance. The Oracles informed Hercules that his only means of atonement was to enter the service of Eurystheus, the king of Tiryns and Mycenae. Eurystheus assigned Hercules twelve different tasks, all of them impossible for regular folk, but only exceedingly difficult for the fiercely strong and determined Hercules. These chores, now called “labors,” included the capture of the hell-hound Cerebus; the slaughter of the Nemean Lion Leo; and the capture of Hippolyta’s Belt. Hippolyta was queen of the legendary Amazons, a race of warrior women not terribly keen on men, particularly those who nick pieces of their garments

After more than a dozen arduous years, Hercules completed these labors. Not only did he atone for his crimes with their completion, but he ascended to the level of an Olympian god and became immortal. Gifted with this immortality, he embarked on many other adventures, many still as perilous as the labors, but not nearly as famous.

None of these exploits killed him, but he eventually did come to a tragic end due to the machinations of the centaur Nessus. To make a wild story pleasantly short, Hercules and his new bridge, Deianeira, were walking through the wilderness and happened on a river torn by strong currents. Nessus offered to convey each of them across to the opposite shore. They readily agreed and Nessus carried Deianeira first. When arriving at the other bank, Nessus attempted to assault Deianeira and was promptly struck by Hercules’ arrow. As the enraged Hercules swam furiously across the river to finish him off, Nessus confided in Deianeira, who, for some reason, trusted the wretch. Nessus advised her to stow away from of his blood for he told her it was an effective love potion. If she ever suspected that Hercules had fallen out of love with her, she was to smear the blood on his coat. On wearing the coat, Nessus’ blood would seep into Hercules skin and induce a powerful love charm on him. Deianeira immediately gathered some of Nessus blood together and hid it on her person just before Hercules reached them and swiftly killed the centaur. A few years later, Hercules’ love for Deianeira was waning and he became cold and distant. One night while Hercules slept, Deianeira rubbed the centaur blood inside her husband’s lion hide coat. When Hercules put it on the next morning, he experienced excruciating pain, for the blood was not a love potion, but a poison that ripped the flesh right off his bones. He was in such dire agony that he begged the gods to make him mortal and let him die. Such as Zeus’ love for his son that he granted the request. Hercules’ mangled body was foisted onto a burning pyre and Deianeira, realizing that she had unwittingly caused Hercules’ death, threw herself onto the pyre with him.

Hercules Constellation, Alpha Herculis, List of Stars in Hercules, Hd 149026 B, Hd 155358, Hd 156668, Beta Herculis, Gd 358, Abell 39

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