Thousands and thousands of brilliant stars make up the globular cluster Messier 53, captured with crystal clarity in this image from Hubble. Bound tightly by gravity, the cluster is roughly spherical and becomes denser toward its heart. This image is a composite of multiple images taken in visible and infrared wavelengths of light.
Discovered by the German astronomer Johann Elert Bode in 1775, M53 is 59,700 light-years away, one of the most distant globular clusters from Earth. Best observed in May, it has an apparent magnitude of 8.3 and can be seen through a small telescope in the constellation Coma Berenices. Larger instruments will resolve the cluster’s individual stars.
Globular clusters are much older and larger than open clusters, so they are generally expected to contain more elderly, red stars and fewer young, blue stars. But Messier 53 has surprised astronomers with its unusual number of a type of star called blue stragglers. All the stars in a globular cluster are expected to form around the same time, so they are expected to be roughly the same age. But blue stragglers appear to be brighter and more youthful than they should be. Although their precise nature remains mysterious, these unusual objects are probably formed by close encounters, possibly collisions, between stars in the crowded centers of globular clusters like M53.
For more information on Hubble’s observations of M53, see: