Collision With NASA Spacecraft Altered Shape of Asteroid Dimorphos

The last complete image of asteroid moonlet Dimorphos, taken by the DRACO imager on NASA's DART mission 12 kilometers from the asteroid and 2 seconds before impact, showing a patch of the asteroid that is 31 meters across, released on Sept. 26, 2022. NASA/Johns Hopkins APL/Handout via Reuters

WASHINGTON—When NASA sent its DART spacecraft to slam into the asteroid Dimorphos in 2022, the U.S. space agency demonstrated that it was possible to change a celestial object’s trajectory, if needed, to protect Earth. It turns out that this collision changed not only the asteroid’s path but its shape as well.

The asteroid, which before the DART encounter looked like a ball that was a bit plump in the waist, now appears to be shaped more like a watermelon—or, technically, a triaxial ellipsoid, scientists said on Tuesday.