An asteroid dissolving into smaller pieces is not an unusual occurrence, but scientists recently observed one break up in a way they had never seen before.
"Seeing this rock fall apart before our eyes is pretty amazing," said University of California, Los Angeles professor David Jewitt.
Astronomers witnessed this asteroid coming apart, not as a result of an impact, but likely due to sunlight. The sunlight is thought to have sped up the rate of the asteroid's rotation, causing weaker pieces on it to fall away at a slow rate. It's the first time scientists have observed this. (Image source: NASA, ESA, D. Jewitt (UCLA))
In short, the asteroid came apart gradually, not as the result of an impact.
The asteroid, P/2013 R3, was first identified in September 2013 and later examined further with the Hubble Space Telescope.
"With its superior resolution, space telescope observations soon showed there were really 10 embedded objects, each with comet-like dust tails. The four largest rocky fragments are up to 400 yards in diameter, about four times the length of a football field," Jewitt said.
The fragments drifted from each other at a relaxed 1 mile per hour pace. This slow speed suggested to astronomers that it was breaking up naturally, not as the result of a collision, which would likely drive the pieces further away at a faster pace.
Researchers believe it was coming apart due to sunlight, which caused the asteroid's rotation rate to increase, thus leading centrifugal force to pull at the pieces. Scientists have previously speculated this could happen but had not observed it.