Most galaxies are elliptical. Some elliptical galaxies are nearly circular in shape. Some elliptical galaxies are extremely stretched out, flattened,or elongated. To deal with this variation, Hubble divided the "E" classification into 8 sub-groups, which he called "E0", "E1", "E2", "E3", "E4", "E5", "E6", and "E7".

E0 galaxies are nearly circular in shape. E1 galaxies are stretched out a little. E2 galaxies are more elongated, E3 galaxies even more elongated or flattened, all the way up to E7 galaxies, which are extremely elongated or stretched out.

Look at these examples:"E1", "E2", "E3", "E4", "E5".

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