Skip to content

Hercules Globular Cluster

The Keystone

  • by
keystone in hercules

The Keystone is an asterism formed by four relatively bright stars in the constellation Hercules: Pi, Eta, Zeta and Epsilon Herculis. The trapezoid-shaped pattern makes it easy for observers to identify the constellation and to find several well-known deep sky objects. On a clear night, the Keystone can be seen between the bright Vega, the brightest star in Lyra, and the stars of Corona Borealis, the Northern Crown. The asterism represents Hercules’ torso.
Read More »The Keystone