Galaxies

Galaxies are enormous structures made up of stars, gas, and dust held together by the gravitational attraction between their individual parts. Small dwarf galaxies may contain several million stars while the larger ones are host to trillions of stars. Until fairly recently, galaxies were thought to be nebulas within our own stellar neighborhood. In the 1920’s, Edwin P. Hubble’s study of the Andromeda Galaxy shed new light on how incredibly far away galaxies are from us. About 10 billion galaxies were thought to exist but pictures taken in 1996 by the Hubble Space Telescope have changed that number to 50 billion.

Our solar system is in the Milky Way galaxy. The Milky Way is a spiral galaxy similar to the one shown at left.

Galaxy: NGC 4414 in the constellation Coma Berenices
Galaxy type: Spiral
Distance from Earth: 62,000,000 light years
Galaxy Diameter: 56,000 light years

Photo source: NASA and The Hubble Heritage Team (STScI/AURA)