Messier 15 is a massive globular cluster orbiting in the Milky Way’s halo. Hundreds of thousands of old stars are compressed into a brilliant, compact swarm roughly 33,600 light-years from Earth.

M15 is a core-collapsed cluster: gravity has packed its center so tightly that the stellar density rises dramatically toward the middle. That concentration creates the blazing core and finely resolved halo visible in this photograph.

Its ancient, metal-poor stars formed early in the history of the Milky Way. Globular clusters like M15 preserve a record of the Galaxy before generations of stars enriched interstellar space with heavier elements.

M15 lies within Pegasus, the winged horse of Greek mythology. Pegasus sprang from the blood of Medusa and later carried the hero Bellerophon into battle against the fire-breathing Chimera.

The cluster has no ancient myth of its own because it is too faint for the unaided eye. Jean-Dominique Maraldi discovered it in 1746, and Charles Messier added it to his catalog in 1764—placing a telescopic discovery inside one of the sky’s oldest legendary figures.

No traditional Hawaiian name is known for M15 itself. From Hawaiʻi, Pegasus climbs prominently into the eastern evening sky through late summer and autumn.