Globular Cluster Messier 79 (M79)

This image of a blizzard of stars resembles a swirling snowstorm in a snow globe. The stars are residents of the globular star cluster Messier 79, or M79. The cluster is also known as NGC 1904. Most globular clusters are grouped around the central hub of our pinwheel-shaped galaxy. However, M79's home is nearly on the opposite side of the sky from the direction of the galactic center. One possibility is that M79 may have formed in an unusual dwarf galaxy that is merging with the Milky Way. In the image, Sun-like stars appear yellow. The reddish stars are bright giants that represent the final stages of a star's life. Most of the blue stars sprinkled throughout the cluster are aging "helium-burning" stars. These bright blue stars have exhausted their hydrogen fuel and are now fusing helium in their cores. A scattering of fainter blue stars are "blue stragglers." These unusual stars glow in blue light, mimicking the appearance of hot, young stars. Blue stragglers form either by the merger of stars in a binary system or by the collision of two unrelated stars in M79's crowded core.