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Runaway Planets

May 10, 2012

Under some circumstances, planets could be thrown out of the galaxy at tremendous speed.

Transcript

BOB HIRSHON (host):

When planets break loose.  I’m Bob Hirshon and this is Science Update.

Our Milky Way galaxy may occasionally hurl planets into deep space at breathtaking speeds.  This according to Dartmouth College and Harvard-Smithsonian astrophysicist Idan Ginsburg.  It’s been shown that this can happen to stars, if they drift too close to the black hole at the center of the galaxy. Now, Ginsburg’s team has calculated that planets orbiting such a star could meet a similar fate.

IDAN GINSBURG (Dartmouth College/Harvard-Smithsonian Center for Astrophysics):

We ran thousands and thousands of simulations, and one of the things that we saw is that not only can these planets get ejected, but under certain circumstances they can get ejected at tremendous velocity, approaching 30 million miles per hour.

HIRSHON:
That’s over 300 times as fast as the Earth orbits the Sun.  For further proof, Ginsburg says runaway planets would have to be detected indirectly, by measuring dips in brightness of the stars they’re ejected with.  I’m Bob Hirshon for AAAS, the Science Society.

An artist's rendering of a runaway planet. (David A. Aguilar/ Harvard-Smithsonian Center for Astrophysics)