Galaxies
Permanent link to the version from 5 Nov 2026, 16:32.
A galaxy is a huge collection of stars, stellar remnants, gas, dust and dark matter held together by gravity. Our Solar System lies inside a barred spiral galaxy, the Milky Way.
Types
Edwin Hubble sorted galaxies by shape in the 1920s, and his scheme is still in use.
- Spiral galaxies have rotating discs with winding arms.
- Elliptical galaxies are smooth and contain mostly older stars.
- Irregular galaxies have no clear form.
Scale
Galaxies range from dwarfs with a few million stars to giants with trillions. Most large galaxies appear to have a supermassive black hole at their centre.