Hubble reveals star cluster Messier 79 doing snow globe impression

Dec. 12 (UPI) -- A Hubble Space Telescope image features the star cluster Messier 79 doing its best snow globe imitation. The mass of stars is a "globular" cluster, after all.

Globular clusters are gravitationally bound collections of stars. The cluster most recently framed by Hubble's lens hosts roughly 150,000 stars -- small potatoes compared to some clusters, which can feature up to a million stars.

M79's stars are packed into a sphere-like shape stretching just 118 light-years across. The star globe is positioned within the constellation Lepus, 41,000 light-years from Earth.

Stellar clusters are typically centered around the central hub of our spiral galaxy, the Milky Way, but Messier 79 -- sometimes called NGC 1904 -- is found far from our galactic center. Some astronomers estimate the cluster formed around a dwarf galaxy that's being subsumed by the Milky Way.

The Hubble's image -- shared this week by NASA -- is a composite of observations captured in 1995 and 1997 by the telescope's Wide Field Planetary Camera 2.

Stars most like our own sun appear yellow, while red stars represent older stars nearing the latter stages of their lifespan.

The image also features blue stars, usually a sign of newborn stars. But the blue stars within M79 are older. Some are "helium-burning" stars that have run out of helium. These aging stars have begun to fuse helium in their core. Others are "blue stragglers," formed by the collision of a binary pair or two unrelated stars.