Seyfert's Sextet is a group of galaxies in which gravitational forces are exerted between its members. There are seemingly six members, but closer inspection reveals only four. One is far more distant then the others and does not play a role in the interaction. Another is not a galaxy in its own right but rather a string of stars torn loose from one of the other galaxies by gravitational pull. The group was discovered by Carl Keenan Seyfert in the 1940s. Scientists speculate that the tearing apart will continue for hundreds of millions of years, and that ultimately the group will transform into one giant elliptical galaxy.
See also: Timeline of galaxies, clusters of galaxies, and large-scale structure