The Andromeda galaxy, M 31, is the nearest spiral galaxy neighbor of the Milky Way. By studying M31 it's like looking at the Milky Way from the outside, and structures and objects hidden in the Milky Way by intervening clouds of gas, dust and stars can be seen clearly in Andromeda. A similar object is thought to live at the center of the Milky Way, but it's harder to see as clearly.
Astronomers think that the black hole glows in X-rays as it swallows nearby clouds of gas and stars.
At a distance of 2.5 million light years from us, the earth is safely beyond the pull of the M31 black hole. The other bright sources in the image are probably solar mass neutron stars orbiting relatively normal stars. Cosmic Journeys Part of the NASA OSS Structure and Evolution of the Universe theme.