Hercules is one of the 88 modern constellations that are among the 48 constellations cataloged by 2nd century astronomer Ptolemy. It is named after the Roman mythological hero adapted from the Greek hero Heracles. It is a northern constellation that lies just off of the Summer Triangle, and near Ophiuchus. Hercules reaches its highest nightfall ascension in July. A squarish asterism called the Keystone is likely to catch the eye first when looking in this area. Older visualizations of this constellation depict the Keystone as Hercules’ hips, while some more modern visualizations depict the Keystone as Hercules’ head.
One of the most notable Messier objects, the Hercules Cluster (M13), is a bright globular star cluster that can be seen with the naked eye in dark skies. It is located between the two stars comprising the Keystone’s western edge. M92 is the only other Messier object in this constellation. The largest and most massive known structure in the universe, The Hercules-Corona Borealis Great Wall, is a filament of galaxies that is situated on Hercules’ border with Corona Borealis.
© James R. Johnson, 2014.