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ITHACA, NY - EMBARGOED FOR RELEASE: 2pm EST, 11 APRIL 2002
Binary asteroids - two rocky objects orbiting about one another - appear to be common in Earth-crossing orbits, astronomers using the world's two most powerful astronomical radar telescopes report. It is probable, they say, that these double asteroid systems have been formed as a result of gravitational effects during close encounters with at least two of the inner planets, including Earth.

 
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Writing in a report published by the journal Science on its Science Express web site, the researchers estimate that about 16 percent of so-called near-Earth asteroids (NEAs) larger than 200 meters in diameter are likely to be binary systems, with about a three-to-one relative size of the two encircling bodies.
 
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