Image of the Day
This is what happens when galaxies collide
(http://bruce.org.uk/images/galaxiescollide2.jpg)
Arp 148 is the staggering aftermath of an encounter between two galaxies, resulting in a ring-shaped galaxy and a long-tailed companion. The collision between the two parent galaxies produced a shockwave effect that first drew matter into the center and then caused it to propagate outwards in a ring.
Awesome!
Courtesy of NASA