So galaxies are giant clusters of stars and dust and gas and dark matter. Most of the galaxies we know about are the shape of our own galaxy, the Milky Way, and they are a spiral shape. Other galaxies can be elliptical or ring-shaped but they are extremely diverse – coming in various colours, shapes and sizes. It is estimated that there are around 170 billion galaxies in the observable universe, so who knows what could be beyond that. Some of their names include: Cartwheel galaxy, Sunflower galaxy and Tadpole galaxy, so I guess their names must come from the shapes they make.
I think’s Clare’s covered it well. If I had to add anything it’s that there is actually a classification system developed way back in 1936 by Edwin Hubble. It’s also called Hubble’s tuning fork diagram cause it kinda looks like one: http://science.howstuffworks.com/dictionary/astronomy-terms/galaxy1.htm
Basically various degrees of round to elliptical, spiral, and spiral with arms and then there’s irregular. Also taking into account whether or not there’s a bulge in the middle, how tightly or loosely wound the spirals are etc. No wonder there are so many colloquial names!
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