Asterisms · Asterism · 4 stars across Hercules
Asterism
Keystone
The Keystone: four stars in a lopsided square that make Hercules’ body, and the way to his great cluster.
- Stars
- 4
- Constellation
- Hercules
- Spans
- about 9° of sky
- Highest at midnight
- early June
Look for
The Great Cluster is a third of the way from Eta Herculis to Zeta Herculis, on the Keystone’s western side.