The Universe's Scale: Galaxies, Stars, and Beyond

[bassplayer142]

If you look at the planets, they group into a star, which all form a galaxy. It just seems like everything groups together. Our observable universe with the Hubble isn't as enormous as the universe may be. If so, galaxys would form an even greater cluster and so on and so forth.

 

[christianjb]

It's called gravity!

 

[russ_watters]

There are galaxy clusters and superclusters, yes.

 

[Robert J. Grave]

Galaxies probably form around very dence black holes to begin with. The black holes probably formed at the earliest stage of the expansion when things were very close together bringing about the galactic formations. Solor systems form around massive bodies such as suns in the same way. All because of gravity.