Most of the galaxies in the Universe have a spiral shape. It’s not clear why that is so, but that is not the point. The point of this exercise is to be able to understand what spiral is, draw it and marvel at the fact we’re living inside one giant spiral called the Milky way.
That, and we have a super massive black hole in the center of the galaxy called “Sagittarius A*”. How’s that for some bed time story!