Galaxies

The Universe is made up of billions of stars that are grouped together into enormous collections called galaxies. Astronomers believe that, on average, a galaxy contains in the region of 100 billion stars, is about 100,000 light years (see Years and Light Years) in diameter and that there are about 100,000 million galaxies, of which our own galaxy, the Milky Way, is but just one. The Milky Way is spiral in shape (galaxies can be spiral, elliptical or irregular in shape), rotates about a central point and contains about 200,000 millions stars, with our Sun being one of them. Galaxies are not stationery and, like all galaxies, the Milky Way is continually moving about in space. It takes the Sun about 220 million years to make one circuit around its central point in the Milky Way.