The
observable universe consists of the galaxies and other matter that can, in principle, be observed from
Earth at the present time because light and other signals from these objects have had time to reach Earth since the beginning of the
cosmological expansion. Assuming
the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe is a spherical volume (a
ball) centered on the observer. Every location in the
Universe has its own observable universe, which may or may not overlap with the one centered on Earth.