Researchers watched an asteroid mysteriously break up into at least 10 pieces.
Scientists have seen "fragile comet nuclei" disintegrate when extremely close to the Sun, but this breakup occurred in the asteroid belt, a Hubble news release reported.
"This is a rock. Seeing it fall apart before our eyes is pretty amazing," David Jewitt of UCLA, who led the astronomical forensics investigation, said in the news release.
When researchers first spotted the object, dubbed P/2013 R3, on Sept. 15 it was described as an "anomalous, fuzzy-looking object," the news release reported. The researchers performed a follow0up observation at the W. M. Keck Observatory in Hawaii.
"Keck showed us that this thing was worth looking at with Hubble," Jewitt said. With its superior resolution, Hubble observations soon showed that there were really 10 embedded objects, each with comet-like dust tails. The four largest rocky fragments are up to 200 yards in radius, about twice the length of a football field."
The observation showed the asteroid pieces slowly drifting away from each other at about one mile per hour, this is slower than a "strolling human."
The slow pace of the broken pieces suggests the asteroid disintegration did not occur as a result of a collision with another object.
The idea that the asteroid could have exploded from pressure caused by warming interior ices was also ruled out because the object was too cold and far away from the Sun for this to occur.
The researchers believe the event may have occurred because of a "subtle effect of sunlight," the news release reported. This effect would cause the asteroid's rotation rate to slowly increase; centrifugal force would cause the pieces to pull apart "like grapes from a stem."
In order for this to occur the asteroid must already have a shattered interior from past collisions with other objects.
"With the previous discovery of an active asteroid spouting six tails (P/2013 P5), astronomers are seeing more circumstantial evidence that the pressure of sunlight may be the primary force that disintegrates small asteroids (less than a mile across) in the solar system," the news release reported.
