Hercules is the fifth largest of the 88 modern constellations. It was also one of Ptolemy's 48 constellations. It was named after the Roman name (Hercules) of the Greek mythological hero Herakles.
Notable features
It has no first magnitude stars. Mu Herculis is 27.4 light years from Earth.
Notable deep sky objects
Hercules contains two of the most conspicuous globular clusters: M13, the brightest globular cluster in the northern hemisphere, and M92.
Mythology
Hercules (Roman, Herakles in Greek mythology) was the demigod son of Zeus and Alcmene. He was, arguably, the greatest of the mythical Greek heroes, best known for his superhuman strength. Many stories are told of his life, including the story of The Twelve Labours.
However, such visualisation was much later, as some parts require quite faint stars to be included, including those which have Flamsteed numbers but not Bayer designations. Earlier views of the constellation held it to be various things, predominantly a stag. Together with the constellation Sagitta, and the association of this area of the sky (the Zodiac of Scorpio) with Artemis, this may be the origin of the myth of the Cerynian Hind, one of The Twelve Labours of Herakles.
Graphic visualization
The stars of the constellation Hercules can be connected in an alternative way, which graphically shows the hero in an athletic pose and holding a club.
The hero's head is traced by a quadrangle of stars: Pi Herculis, Eta Herculis, Zeta Herculis and Epsilon Herculis. This quadrangle lies between two very bright stars: Vega on the constellation Lyra and Gemma on the constellation Corona Borealis.
The hero's right leg contains two bright stars of the third magnitude: Alpha Herculis (a.k.a. Ras Algethi) and Delta Herculis (a.k.a. Sarin). Delta Herculis is the right knee.
The hero's left leg contains dimmer stars of the fourth magnitude which do not have Bayer designations but which do have Flamsteed numbers.
The star Beta Herculis belongs to the hero's outstretched right hand, and is also called Kornephoros.
The Globular Cluster M13 lies on the top of the hero's head, between the stars Eta Herculis and Zeta Herculis . It is dim, but may be detected by the unaided eye on a very clear night.
Reference
- H. A. Rey, The Stars — A New Way To See Them. Enlarged World-Wide Edition. Houghton Mifflin, Boston, 1997. ISBN 0-395-24830-2.