A quasar is a high-energy source that is extremely bright and extremely distant. Quasars are approximately the same size as the solar system. Their light must travel billions of years to reach Earth. That means quasars are extremely old. The wavelength of light coming from quasars has been transferred to the red end of the spectrum. Quasars might be galaxies in a(n) infant stage. Many astronomers believe that when galaxies collide they could feed material to supermassive black holes. These black holes would feast on entire stars. This would release enormous amounts of energy. Some photographs from the Hubble telescope support this hypothesis.