Hubble catches break-up of asteroid on film

Experts pictured the P/2013 R3 asteroid using Nasa’s Hubble Space Telescope.

Publishing details of what they witnessed in Astrophysical Journal Letters, they said that though fragile comet nuclei have been seen falling apart as they near the sun, nothing resembling this type of breakup has been observed before in the asteroid belt.

The pictures show the asteroid splitting up into smaller fragments between October last year and mid-January.

The four largest rocky fragments are up to 200 yards in radius, the astronomers said.

They said that the debris of the asteroid will provide a “rich source of meteoroids” in the future. While most will plunge into the sun, a small fraction may one day enter the Earth’s atmosphere as meteors.

“Seeing this rock fall apart before our eyes is pretty amazing,” said Professor David Jewitt, of the University of California, Los Angeles.

Fragments were seen drifting away from each other at a pace of about of one mile per hour.

The astronomers said the asteroid began coming apart early last year, but new pieces continue to emerge in the most recent images.

They said it was unlikely that the asteroid is breaking up because of a collision with another, because that would have caused an “instantaneous and violent” break up.

They said that the break up is also unlikely to have been caused by interior ices warming and vaporising because it is too cold – being nearly 300 million miles from the sun.

Prof Jewitt, who led the astronomical forensics investigation into the asteroid, said that it could have disintegrated due to a “subtle effect of sunlight”.

He said that this can cause the rotation rate to slowly increase which causes the asteroid’s component pieces to gently pull apart due to “centrifugal force”.

This type of disruption has been discussed by experts for several years but so far never been reliably observed.