Question: What do all the galaxies look like?

Jen Gupta answered on 15 Jun 2011:

Galaxies mainly come in two types – spiral galaxies and elliptical galaxies.

Spiral galaxies are like our Milky Way and have a central bright bit that we call the bulge and then arms of stars spiralling out. They normally look blue and this is because the stars in spiral galaxies are young. My favourite examples of spiral galaxies are the Whirlpool galaxy and the Pinwheel galaxy. Not all spiral galaxies look the same, we classify them based on how tightly wound the spiral arms are and if they have a bar of material going across the middle.

Elliptical galaxies just look like blobs of stars! They usually are red because the stars in elliptical galaxies are older. We classify elliptical galaxies by how round or elliptical they look. There aren’t as many pretty pictures of elliptical galaxies around, I guess because most people think they aren’t as interesting to look at as spiral galaxies. The largest galaxy that we know of is a giant elliptical galaxy called IC 1101 in a cluster of galaxies called Abel; 2029.

Then there are strange galaxies that don’t fit into these two categories – we call these irregular galaxies. I think these are my favourite because they all look different and some of them look really cool! The most famous is probably the antennae galaxies. Galaxies can be irregular because of a collision with another galaxy or because another galaxy near to it has such strong gravity that the galaxy gets distorted.

The classifications of galaxies based on what they look like was first done by an astronomer called Edwin Hubble and it’s known as the Hubble sequence.

Of course, all of this is just based on the galaxies that we can see – we don’t know what *all* the galaxies look like because there are galaxies that we haven’t seen yet! Also recently spiral galaxies that are red instead of blue have been found so galaxies aren’t as simple as they might seem!