The Mice colliding galaxies optical image taken by the Hubble Space Telescopes new Advanced Camera for Surveys ACS on April th These galaxies NGC were once spiral in shape but the gravitational interaction has thrown off long tails of stars and distorted their nuclei yellow It has also caused a burst of star formation activity as seen by the abundance of hot young blue stars The galaxies will combine to form one large elliptical galaxy in several million years time The Mice are around million light years from Earth in the constellation Coma Berenices