One of the nearest and youngest examples of a pair of colliding galaxies, the Antennae Galaxies began to interact some 200 - 300 million years ago. The brightest and most compact of these star birth regions are called super star clusters. Nearly half of the faint objects in the image are young clusters containing tens of thousands of stars. The orange blobs to the left and right of image center are the two nuclei or cores of the original galaxies and consist mainly of old stars criss-crossed by filaments of brown dust. The two galaxies are dotted with brilliant blue star-forming regions surrounded by glowing pink hydrogen gas.