This galaxy resembles a bull's eye, which is appropriate because its appearance is partly due to a smaller galaxy that passed through the middle of this object.
The violent collision produced shock waves that swept through the galaxy and triggered large amounts of star formation.
X-rays from Chandra (purple) show disturbed hot gas initially hosted by the Cartwheel galaxy being dragged over more than 150,000 light years by the collision.
Optical data from Hubble (red, green, and blue) show where this collision may have triggered the star formation.
