Globular clusters can be found in the halo of bright galaxies, such as the Milky Way. Many of the globular clusters within the Milky Way are located around its galactic core.
There are about 150 known globular clusters that can be found in the Milky Way, with as many as 20 globular clusters thought to be undiscovered. Larger galaxies can have many more than this. The Andromeda galaxy is believed to have as many as 500. Galaxy M87 is a giant elliptical galaxy that is theorized to have more than 10,000 globular clusters.
The term "globular cluster" comes from the Latin word "globulus," which means "small sphere." This is because a globular cluster is a spherical combination of stars that are dense and bound together tightly by gravity. The tight gravitational field that binds the collection of stars together is thought to give the globular cluster its spherical shape.
While not all galaxies contain globular clusters, the stars in a globular cluster are older than other stars in the galaxy, such as those stars that are found within the disk of a galaxy in open clusters. While astronomers theorize that globular clusters contain the first stars produced in a galaxy, their origin and evolution is not currently known.