just 2.5 miles across, Gault is spinning so quickly that it has begun to slowly shed surface material (rock and dust grains called regolith), leaving a long trail of dusty particle behind.
The fascinating issue regarding this unravelling asteroid is that the soiled trash broken off of its spinning surface is really streaking behind it, forming two comet-like tails that give it an eerie, almost ethereal look.
These bright streaks of material have been caught on camera by the Hubble Space Telescope, which observed the asteroid in the throes of self-destruction and managed to snap a clear photo of its long, thin debris tails.
The spectacular snapshot was released yesterday by NASA and is completely bewildering. “Each tail represents Associate in Nursing episode within which the asteroid gently shed its material — key proof that Gault is setting out to split up.”
Interestingly enough, the asteroids comet-like tails originated a few months apart and sport a significant difference in size.
While both of them share a mysterious resemblance to the coma of a comet, the longer tail stretches more than 500,000 miles and is roughly 3,000 miles wide. Meanwhile, the shorter tail is about a quarter as long.
Hubble photo of self-destructing asteroid Gault, which is slowly shedding surface material into two comet-like tails of debris. NASA, ESA, K. Meech and J. Kleyna (University of Hawaii), and O. Hainaut (European Southern Observatory)
Short for “Yarkovsky–O’Keefe–Radzievskii–Paddack” (the names of the scientists who contributed to the concept), the YORP effect causes asteroids to continually spin faster as a result of the tiny torque produced when their surface is heated by the sun and begins to leak infrared radiation, which carries off both angular momentum and heat.
This allows the trash to step by step accumulate behind the asteroid, creating the fantastic comet-like tails captured in the Hubble photo.
Olivier Hainaut of the European Southern Observatory in Germany, a member of the Gault observing team, pointed out that the asteroid’s tails are neatly organized, with 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 quickest by pressure from daylight.”
While astronomers have known about the existence of Gault for a little over three decades – the asteroid was first discovered in 1988 – it is only recently that the space rock has begun its process of self-ruin.
In fact, clues about its strange behaviour were only picked up earlier this year, when Gault was imaged by the ATLAS telescope in Hawaii – a NASA-funded asteroid-tracking observatory that stands for Asteroid Terrestrial-Impact Last Alert System.
Gault’s long tail was spotted by ATLAS on January 5. The intriguing discovery prompted astronomers to take a look at archival data.
The second, shorted tail was detected about two weeks later by the Canada–France–Hawaii Telescope in Hawaii and the Isaac Newton Telescope in Spain.
The finding piqued astronomers’ interest to such an extent that various observatories all across the globe – as well as all-sky surveys and space telescopes – rallied behind the effort to study Gault’s unusual
After analyzing the data, researchers traced back the origin of the asteroid’s tails to two dust events that occurred last year, one around October 28 and the other around December 30.
“The asteroid’s slim streamers counsel that the mud was free briefly bursts, lasting anyplace from many hours to many days,” notes NASA.
“These sudden events puffed away enough debris to make a ‘dirtball’ approximately 500 feet across if compacted together.”
As the space agency points out, Gault is the second known asteroid in which scientists have observed the YORP effect.
“This self-destruction event is rare”, said Hainaut, noting that “active and unstable asteroids, such as Gault, are only now being detected by means of new survey telescopes that scan the entire sky.” “That means that all these asteroids that start misbehaving get caught.”