Elliptical galaxies are named depending on their shape. Some elliptical galaxies are ball-shaped. These are called E0 galaxies. Others are more flat like an egg. The flattest are called E7 galaxies. The ones in between are given numbers from E1 to E6.
The system is useful because it tells us how a galaxy looks through a telescope. This picture is of an elliptical galaxy called Messier 59 (SEDS Archive). It is an E5 class, and is much flatter than the E0 galaxy called Messier 32 at the top of this page.
Elliptical galaxies donít have easily seen shapes like spirals. They are just big collections of stars that are held together by gravity.
Elliptical galaxies have older stars than spiral galaxies. Not many new stars are made in elliptical galaxies because they have less dust and gas.
Some elliptical galaxies are much bigger and heavier than spirals, but others are much smaller and lighter. The big ones are usually very bright, while the smaller ones are much fainter.
Astronomers believe that because they have older stars, elliptical galaxies were made before spirals.
The picture on the right (©AAO) shows the giant elliptical galaxy M87 (type E1). M87 is a very unusual galaxy. In 1918 astronomers found a huge jet of gas coming from the middle of the galaxy. Pictures from the Hubble Space Telescope now seem to show an enormous black hole in the middle.
Author: Nigel Bannister
Updated by: Carolyn Brinkworth and Claire Thomas
Last updated: July 2001