This image captures an enormous cataclysm: the spectacular collision of two galaxies. Astronomers believe the encounter between these galaxies (collectively known as NGC 4038 or the Antennae  Galaxies) began some 500 million years ago.
    The bright spots are groups of newly formed stars. The spots between the galaxies are particularly interesting: here shock waves from the collision have caused clouds of dust and gas to contract into stars—a fairly strong indication that the galaxies are actually colliding, not just acting on each other gravitationally.