galaxies are huge congregations of stars held together by force of gravity. they are so big that they have sometimes been called island universes. studies of distant spaces with optical and radio telescopes indicate that there may be about 100 billion galaxies in the visible universe.galaxies semm to be scattered in space and tend to be grouped together into clusters. and some clusters appear to be grouped into superclusters.
when the expandiny material of the universe broke up in the first instance, billions of islands of gaseous matter were formed in space. these gaseous islands or proto-galaxies rotated,each with its own speed of rotation.those with very low rotational speeds assumed nearly sperical shapes.very low rotational speeds
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