Globular cluster M4 in the Milky Way

This illustration shows the location of the globular cluster M4 in our Milky Way Galaxy, which is depicted 'edge-on' or from the side. Globular clusters like M4 are the first pioneer settlers of the Milky Way. Many coalesced to build the hub of our galaxy and formed billions of years before the appearance of the Milky Way's magnificent pinwheel disk. Today, 150 globular clusters survive in the galactic halo.