Asterism
The Keystone
A lopsided quadrilateral forming the torso of Hercules; the great globular cluster M13 lies along its western side.
Constellations
The constellation this pattern draws its stars from.
An asterism is a recognisable star pattern that is not one of the 88 official IAU constellations. Explore the 88 constellations →
Sources
The primary and reference sources this topic draws on.
- BritannicaEncyclopaedia Britannica
General reference for the history of astronomy, biographies, and cultural context.