We live in a big-city galaxy. The Milky Way is so big it has satellite galaxies that orbit it, just as the Moon orbits the Earth. These arrangements tell us a great deal about the secrets of the universe—from how galaxies form to the mysterious nature of dark matter.
![](https://scx1.b-cdn.net/csz/news/tmb/2020/groupiegalax.jpg)
Source:
https://phys.org/news/2020-05-groupie-galaxies-orbiting-milky-dark.html