What is a Galaxy ?
Initially, We told that our galaxy was the universe. Then with the telescopes we saw galaxies.
A galaxy are stars that revolve around a black hole, that is to say a gigantic matter’s cluster, so heavy that light does not come out of it.
The galaxy’s black hole, however, is a very small galactic matter’s part. So the galaxy is spinning very fast around the black hole, so fast that it’s flat.
Normally stars should be ejected from the galaxy like a spinning top would. But that’s not the case. So it is believed that there is a soul that maintains the galaxy.
Learn about software that allows you to emulate a galaxy. Jean-Pierre Petit made one.