The mythological hero Hercules is a staple. His strange celestial story is a testament to his greatness.Hercules, one of the most well-known star patterns, stands tall over our heads in this week's Northern Hemisphere nightfall.Hercules, like many other oldest constellations, can be traced back to recorded history around 5,000 years ago in Mesopotamia, the Middle East (the area that we now call Iraq), though we refer to him by his Latin name. Hercules is a symbol of strength and power, and he can be seen in many legends from the region, including the story of Sampson in The Bible.Related: Stargazing maps - Best night sky eventsIt looks like this?There are many ways Hercules can be traced depending on which astronomy guide you are using. You might initially expect this powerful strongman to be a prominent constellation like Orion the Hunter, with his distinctive three star belt.This is false.H.A. H.A. Rey said it best when he stated that Hercules was "... well-known for his strength, but as an constellation he is rather weak without bright stars."Mesopotamian skywatchers 3000 BC observed Hercules standing tall in the northern sky during summer. The third-magnitude Ras algethi, Arabic for "Head Of the Kneeler", is Hercules' brightest Star. Indeed, Hercules is seen in the sky posing on one knee with Ras Algethi (a supergiant red star) marking his head.Over the last 5,000 years, however, the Earth's tilt (or "precession") has caused stars' positions to shift so much that Hercules today appears to be doing acrobatics. His head is well south of the zenith. This means that Hercules is now standing on the top of his head.Rey has reimagined the group of stars in its current orientation, describing it as "a man swinging at a club" and "Hercules’ favorite weapon." Rey's interpretation of the quadrilateral, which was supposed to be Hercules’ waist and hips by the ancients, ends up being his head. The star Ras Algethi, which the ancients thought was the hero's head, marks Hercules’ left foot. Different strokes for different folks.Robert H. Baker, an astronomer, described Hercules in his 1937 book, "Introducing the Constellations", (Viking Press). This figure is somewhat similar to the letter H, which is the initial for Hercules.Legend of HerculesHercules was also known as Heracles in Greek culture. His extensive mythology is among the most well-known of Greek mythology. In keeping with the tradition that Latin names are used for constellations, we call him Hercules.The Romans adopted many Greek heroes, heroes, and legends. They identified them with their own characters. So Zeus became Jupiter, Hera, Juno, Ares, Mars, and so on. The Latin name is preferred when astronomical bodies have been given mythological names in modern times.Lucius Annaeus Seneca, a great Roman writer, statesman, and philosopher (4 BC-AD65), relates in verse some leading Hercules stories in "Hercules Furens," ("Mad Hercules") including a diatribe against Juno's demigod son by another man, the mortal Alcmene.The connection between Hercules is actually made with two other constellations: the Lernean Hydra, a nine-headed serpentine water monster, and a smaller creeping sea creature.Juno, jealous of Hercules's success, summoned Cancer (a crab) to bite Hercules. Her crustacean arrived at the exact moment Hercules was busy killing Hydra, one his 12 superhuman "labors".Cancer's bite was not more than an annoyance to Juno, who rushed to crush the attacker under his heel. Juno, infuriated by the fate of the crab, banished the hapless creature to heaven as one of the most obscure of the traditional constellations.The Hydra was a similar story. Each time Hercules cut off one head, two new heads grew in its place. His nephew Iolaus burned the stumps of each severed neck to ensure that new heads could not sprout. But Hercules won. In the evening sky we see Hercules standing triumphantly high above the heavens. The tail of Hydra, a constellation of the sun, can be seen below the southwest horizon, hurrying to get out of sight.It's a great collection of starsM13, the Great Globular Cluster of Hercules, is the object that draws the most attention and is considered a highlight for Northern Hemisphere observers. It can be found within the Keystone about two-thirds distance from the butterfly’s head, along the western edge the northern wing. It has a total light equivalent to about a sixth magnitude star. This cluster was discovered by Edmond Halley in 1714.M13 lies at a distance of approximately 22,000 light-years. Scientists believe this great globular contains at least hundreds of thousands stars. It will appear as a pale, indistinct glow when viewed through binoculars. The diameter is half the size of the moon. It is a stunning sight when viewed through telescopes. A telescope of only 4 to 6 inches will reveal the outer stars. Larger telescopes, measuring 8 to 12 inches, reveal the captivating beauty of a vast ball of stars.The Hercules Cluster is a well-known object. It is often displayed to anyone who may pay an evening visit to an observatory. The 85th Stellafane Convention will take place next week, August 5-8 in Springfield, Vermont. Weather permitting, amateur astronomers will set-up their equipment under dark New England skies. Or they can gather at McGregor Observatory to view the 13-inch Schupmann telescope and the 12-inch Porter Turret Telescope.A story about Walter Scott Houston, M13 stars deep-sky authority (1912-1993), is a well-told tale. He was known to all as Scotty and had a column in Sky & Telescope for almost half a century.He noticed that there was a long line waiting to see the Porter scope. "What are you guys looking at?" He asked, as he poked through the observatory doors. Several people murmured quietly, M13, as they emerged from the darkness."M13?" Scotty replied with a touch of skepticism. "So many people have seen it that you would think it would be worn out by now!"Joe Rao is an instructor at the Hayden Planetarium in New York. He is a writer on astronomy for Natural History magazine and the Farmers' Almanac, among other publications. Follow us on Facebook and Twitter @Spacedotcom
