Why are there different types of galaxies?

1 Answer
Nov 20, 2015

The collision between the galaxies is basically the reason of their different shape.


The galaxies that have been undisturbed for billions of years are likely to form spiral, disk shaped galaxies.
Smaller galaxies gravitationally attract each other and merge into an elliptical shape. This merging process can go on for billions of years. So the galaxy seems irregular in shape in between a merging process.