Galaxies The Universe is not empty. Rather, it is full of galaxies, which often gravitate together to form clusters. The cluster that we are in is a group of galaxies known as the Local Group, with Andromeda Galaxy at 22 million light years away being the nearest. These clusters also come together to form superclusters. We belong to the Virgo supercluster, a huge cluster of millions of galaxies. Galaxies are star clusters often held together by galactic nuclei. The stars rotate around these nuclei and are kept within the galaxy and not flung away through the gravity of dark matter. The nuclei’s extreme gravity causes these billions of stars to rotate around it continuously. The stars on the other hands may form a solar system. There are many types of galaxies, with different arrangements of space matter, shapes and sizes.
A Flash movie illustrating the size of things in the Universe.
Galaxies | Milky way | More on Milky Way | The Local Group | Types of Galaxies | Structure of galaxies | AGN and Quasars
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