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A comet doubleheader

The first contact binary is discovered — a comet that is two chunks somehow held together

When Comet 8P/Tuttle passed close to Earth early this year, astronomers took its portrait with the Arecibo radio telescope in Puerto Rico. To their surprise, the radar images have revealed that the comet consists of two chunks that appear to be held together by a narrow neck of material.

The portrait suggests that the body is the first known example of a comet that is a contact binary. Researchers aren’t sure how the structure formed.

John Harmon of Arecibo Observatory reported the findings on October 11 in Ithaca, N.Y., at the annual meeting of the American Astronomical Society’s Division for Planetary Sciences.

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