The image below was taken by the Hubble Space Telescope (found at NASA – Image of the Day Gallery). It shows the ‘encounter’ of two galaxies: the collision created a shock-wave that pulled matter into the center and then the matter disseminated outward to form a ring structure. The central bright protuberance that is perpendicular to the ring structure led NASA to believe that the image is a ‘snapshot’ of an ongoing collision. The pair of colliding galaxies is cataloged as ARP 148 (its nickname is Mayall’s object), and it is in the Ursa Major constellation (the Great Bear), five-hundred million light-years from Earth.

Image Credit:

NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

And

A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)