When Galaxies Collide: Beautiful Images of Cosmic Impacts
“As small galaxies merge, they make larger galaxies, and those will then merge to make still larger galaxies, and so on, up to and including the present-day galaxies,” said astronomer Kirk Borne of George Mason University.
Because of the vast distances between them, there’s a low probability that stars within galaxies will actually hit head-on. But gravitational forces can wrest stars from their previous orbits, scrambling the shape of the galaxies involved.
Friction between diffuse gas and dust inside each galaxy raises temperatures, and interstellar material often combines into huge molecular clouds. All this mass in one place triggers prodigious star formation, with stellar birth rates increasing by a hundredfold.
On the following pages, Wired takes a look at some of the most amazing images ever taken of these cosmic pile-ups.
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