Galaxies come in three main shapes. Spiral galaxies – have a thick bunch of stars in the middle surrounded by stars arranged in spiral arms. The stars of the Milky Way form a thick bar-like center surrounded by a spiral of stars. Elliptical galaxies have stars that form shapes like balls or flat discs. Irregular galaxies have stars that do not form any particular shape. Irregular galaxies are less common. Scientists think most irregular galaxies were once spiral or elliptical galaxies, but their shape changed over time because of gravity.
