The Sciences

Collision Course

By Eric PowellNov 1, 2000 6:00 AM


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Heads up— there's a galaxy headed our way. Andromeda is on a collision course, hurtling toward the Milky Way at 300,000 miles per hour. The smashup won't happen for about 3 billion years, but John Dubinski, an astrophysicist at the University of Toronto, has given us a chance to start rubbernecking right now.

Using the Blue Horizon supercomputer at the San Diego Supercomputing Center, Dubinski has simulated what will happen if Andromeda hits our galaxy dead on. At first the galaxies sideswipe each other, their gravitational fields tearing off streamers of stars and nebulae tens of thousands of light-years long. Growing increasingly entangled, the galaxies plunge into one another, smearing their original spiral forms and finally creating a new, elliptical-shaped galaxy.

Our sun should survive the drama just fine. "There's a lot of empty space between stars, so the chances of two stars colliding is almost zero," Dubinski says. Even a close encounter is unlikely. But we might get pulled along one of those streamers into lonely, intergalactic space, where the night sky would be utterly starless. Worse, we might be flung toward the center of the combined galaxy. There, young stars, born during the merger, will explode as supernovas, and a quasar— a giant black hole ignited by the galactic collision— might spew energetic radiation. Dubinski doesn't envy whoever will be around then: "Flying into the middle of that would cause a lot of problems."

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