Author: Jennifer Leman / Source: Science News
WASHINGTON — New up-close images of Bennu have confirmed that the asteroid is shaped like a spinning top.
That look, characterized by a raised equatorial ridge, is shared by other similarly sized asteroids in the solar system including Ryugu, currently being explored by Japan’s Hayabusa2 spacecraft (SN Online: 6/27/18). NASA’s OSIRIS-REx spacecraft arrived at Bennu on December 3 (SN Online: 12/3/18).But new observations show that both asteroids are spinning on their axes too slowly to explain their shape, says Hayabusa2’s mission manager Makoto Yoshikawa of the Japanese space agency JAXA. If the rotation is fast enough, momentum can push loose rocks toward the equator, giving an asteroid a spinning-top shape. But Ryugu rotates once on its axis only every 7.6 hours; new data show that Bennu rotates once every 4.3 hours.
With spacecraft now exploring both Bennu and Ryugu, researchers hope to figure out the asteroids’ puzzling appearance. “It’s an asteroid geologist’s dream to have a mystery like…
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