30 March 2019
Washington: NASA's Hubble Space Telescope has captured a small asteroid in the process of spinning fast and throwing off material dusty debris.
The Hubble images from show two narrow, comet-like tails of dusty debris streaming from the asteroid (6478) Gault. Each tail represents an episode in which the asteroid gently shed its material -- key evidence that Gault is beginning to come apart, NASA said in a statement.
Discovered in 1988, the 4-km wide asteroid has is located 344 million km from the sun. Hubbles' images have given astronomers the opportunity to study the makeup of these space rocks without sending a spacecraft to sample them.
"We didn't have to go to Gault," explained Olivier Hainaut of the European Southern Observatory in Germany, a member of the Gault observing team.
"We just had to look at the image of the streamers, and we can see all of the dust grains well-sorted by size.
"All the large grains (about the size of sand particles) are close to the object and the smallest grains (about the size of flour grains) are the farthest away because they are being pushed fastest by pressure from sunlight," Hainaut said.
The researchers estimate that Gault could have been slowly spinning up for more than 100 million years.
Further, the asteroid's surrounding environment revealed no signs of more widely distributed debris, which rules out the possibility of a collision with another asteroid causing the outbursts, NASA said in the statement, reported The Astrophysical Journal Letters.
The asteroid's narrow streamers suggest that the dust was released in short bursts, lasting anywhere between a few hours and a few days. These sudden events puffed away enough debris to make a "dirt ball" approximately 150 metre across if compacted together.
The tails will begin fading away in a few months as the dust disperses into the interplanetary space, NASA said.