AstronomyCast Galaxy

A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an intersellar medium of gas and dust, and dark matter. Galaxies contain various amounts of star remnants, star clusters, and types of interstellar clouds. There are several different types of galaxies including elliptical galaxies, spiral galaxies, ring galaxies, dwarf galaxies, starburst galaxies, and other morphologies. The galaxy in which we live is named the Milky Way galaxy and it is a disc shaped spiral galaxy. It is 100,000 to 200,000  light years in diameter and holds about 200-400 billion stars. It is estimated to be 13.2 billion years old.