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Fasten Your Seat Belt
Colliding Galaxies NGC 4038 and NGC 4039When galaxies collide, strange things happen, much to the delight of astronomers. This is how the Hubble Space Telescope views the Antennae galaxies (so called because of the wispy tails of matter that look like insect feelers). These crashing or "interacting" galaxies is the youngest and nearest (to us) example of a galactic wreck, and from the mayhem scientists hope to find clues to one of the fundamental mysteries of astronomy: why some galaxies are spirals while others are elliptical in shape. Not only does the collision alter the spatial parameters of the galaxies, but it sparks a flurry of star formation, igniting clouds of cold hydrogen gas "like a string of firecrackers" which then collapse to form dense clusters of stars. These cosmic fender benders may also foretell the fate of our own galaxy, the Milky Way, which a few billion years from now is expected to careen into the nearby Andromeda galaxy.

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