A Colorful Collision
Two spiral galaxies in the Canis Major constellation collide in an encounter fraught with supernovae and incredibly bright x-rays.
X-ray binary systems—consisting of one star orbiting a neutron star or black hole—give off these luminous x-rays. The spiral galaxies NGC 2207 and IC 2163 contain one of the largest collections of such systems. (Learn why binary stars are so prevalent.)
Researchers believe these superbright x-rays could be evidence of an as-yet-undiscovered intermediate size of black hole. (Read about black holes in National Geographic magazine.)
The composite image above is a combination of views, with x-rays in pink; visible light in blue, white, orange, and brown; and infrared light in red.
—By Jane J. Lee, photo gallery by Mallory Benedict
Week's Best Space Pictures: Galaxies Collide, Gullies Get Frosted, and Cities Light Up
Colliding galaxies put on a show, Martian gullies meet Jack Frost, and cities glitter for the holidays in this week's best space pictures.