6. We’re Surrounded By a Dark Halo
The Milky Way is embedded in a clump of dark matter that is far larger and more massive than the galaxy itself. In the late 1960s, astronomer Vera Rubin inferred the presence of these invisible halos around galaxies when she observed that stars near the edge of Andromeda were whipping around the galaxy’s center at speeds that should send them flying off into space. And yet, they weren’t, meaning that some sort of cosmic glue held everything together. That glue, we now know, is dark matter.
7. He Hang Out With Ancient Stars
The Milky Way is also surrounded by more than 150 ancient groups of stars, some of which are among the oldest in the universe. Called globular clusters, these primordial stellar conglomerates live in the Milky Way’s halo and orbit the galactic center. Each is crammed with hundreds of thousands of stars. Also hanging around the Milky Way are dozens of satellite galaxies; most of these are tough to see, but the Small and Large Magellanic Clouds glisten each night in the southern sky.