Category:Galaxy

Galaxies are gravitationally bound systems of stars, stellar remnants, interstellar gasses, dust and dark matter. There are between 170 billion and 200 billion galaxies in the universe, ranging from dwarfs with a few thousand stars to giants with hundreds of trillions of stars. Our sun is situated in the Milky Way galaxy.

Galaxies are massive. Most galaxies are between 1,000 and 100,000 parsecs in diameter, although there are smaller, dwarf galaxies that can be as small as 100 parsecs in diameter. Galaxies are often found in groups, called clusters. Our own galaxy cluster is called the Local Group. Galaxy clusters are in turn found in groups, called Superclusters. Our own Supercluster, the Virgo Supercluster, is also part of an even bigger supercluster, known as the Laniakea Supercluster, home to about 100,000 galaxies and a whopping 500 million light years across.

Most galaxies are orbited by smaller satellite galaxies and globular clusters (dense clusters of stars in the otherwise near-empty galactic halo.

Galaxies are categorized based on their shape.