WebGalaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many are thought to have supermassive black holes at their centers. The Milky Ways central black hole, known as Sagittarius A, has a . WebJul , A galaxy is a huge collection of gas, dust, and billions of stars and their solar systems. A galaxy is held together by gravity. Our galaxy, the Milky Way, also has a supermassive black hole in the middle. When you look up at stars in the night sky, youre seeing other stars in the Milky Way.. WebJun , Galaxies are vast cosmic islands of stars, gas, dust, and dark matter held together by gravity. Hubbles keen eye has revealed intricate details of the shapes, structures, and histories of galaxies whether alone, as part of small groups, or within immense clusters.. WebNamed galaxies. This is a list of galaxies that are well known by something other than an entry in a catalog or list, or a set of coordinates, or a systematic designation. Image. Galaxy. Constellation.