Mice Galaxies

NGC 4676, or the Mice Galaxies, are two spiral galaxies in the constellation Coma Berenices. About 290 million light-years away, they began the process of colliding and merging about 290 million years ago. Their name refers to the long tails produced by tidal action—the relative difference between gravitational pulls on the near and far parts of each galaxy—known here as a galactic tide. Members of the Coma cluster, it is a possibility that both galaxies have experienced collision, and will continue colliding until they coalesce.

The colors of the galaxy are peculiar. In the upper galaxy (NGC 4676A, to the right in the photo), a core with some dark markings is surrounded by a bluish white remnant of spiral arms. The tail is unusual, starting out blue and terminating in a more yellowish color, despite the fact that the beginning of each arm in virtually every spiral galaxy starts yellow and terminates in a bluish color. The lower galaxy (NGC 4676B, to the left) is closer to normal, with a yellowish core and two arcs; arm remnants underneath are bluish as well.