... The Antennae Galaxies in Collision . ... When two galaxies collide, the stars that compose them usually do not. That's because galaxies are mostly empty space and, however bright, stars only take up only a small amount of that space. ... Polar Ring Galaxy NGC 2685 . ... NGC 2685 is a confirmed polar ring galaxy - a rare type of galaxy with stars, gas and dust orbiting in rings perpendicular to the plane of a flat galactic disk. ... Gamma Rays from Galactic Center Dark Matter . ... A Hole in Mars . ...