Galaxy explained to kids

A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few hundred million (109) stars to giants with one trillion (1012) stars, each orbiting its galaxy's center of mass. Most galaxies are organized into groups, clusters, and superclusters. Our galaxy, the Milky Way, is a typical spiral galaxy and is a part of the Local Group, which includes the Andromeda Galaxy and about 54 other smaller galaxies. There are at least two trillion (2×1012) galaxies in the observable universe. Most of them are organized into a vast cosmic web of filaments and voids.