APOD 18: THE ANTENNAE GALAXIES IN COLLISION

16 March 2014

When two galaxies collide, the stars that compose them usually do not. Galaxies are mostly entirely empty space, and stars only take up minute space. During the slow, hundred million year collision, one galaxy can still rip each other apart gravitationally - dust and gas DO collide. Dark dust pillars mark massive molecular clouds being compressed during galactic encounter, causing rapid birth of millions of stars - some bound in the same massive star cluster.