Globular cluster

A globular cluster is a spherical collection of hundreds of thousands to millions of stars all bound together by gravity, orbiting around the center of a galaxy like our Milky Way. These ancient stellar cities are among the oldest objects in the universe, with stars that formed billions of years ago, and they're so densely packed that near their centers, stars can be separated by distances of just a few light-days rather than the many light-years typical of our cosmic neighborhood. Astronomers find globular clusters fascinating because studying them helps us understand stellar evolution and the early history of galaxies themselves.