, The notion of galaxies is a system consisting of a very large star, dust and gas, where the members have an attractive pull (gravity). A galaxy generally consists of billions of stars that have very diverse colors, sizes and characteristics. Examples of galaxies, such as the Andromeda Galaxy and the Milky Way Galaxy where our solar system is circulating. Galaxies are generally not found in a single form. Most galaxies are clumped in clusters. For example the Milky Way galaxy in a cluster called the Local Group.