NASA said today that the Hubble Space Telescope snapped what the agency called a never-before-seen break-up of an asteroid in mid-space.
The asteroid, designated P/2013 R3 has broken into as many as ten smaller pieces , each with a comet -like tail, that NASA says are drifting away from each other at a leisurely 1.5 kilometers per hour - slower than the speed of a strolling human. The asteroid began coming apart early last year, but the latest images show that pieces continue to emerge.
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"This is a really bizarre thing to observe - we've never seen anything like it before," says co-author Jessica Agarwal of the Max Planck Institute for Solar System Research, Germany in a statement. "The break-up could have many different causes, but the Hubble observations are detailed enough that we can actually pinpoint the process responsible."
The fact that the Hubble is seeing multiple fragments of the asteroid make it unlikely it is disintegrating due to a collision with another asteroid, which would be instantaneous and violent, NASA said.
Rather the asteroid is likely disintegrating due to a subtle effect of sunlight that causes the rotation rate to slowly increase over time. Eventually, its component pieces gently pull apart due to centrifugal force. The possibility of break-up by this phenomenon - known as the YORP effect - has been discussed by scientists for several years but never reliably observed, NASA stated.
NASA says P/2013 R3's debris, weighing in at 200,000 tons, will provide a rich source of meteoroids in the future.
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The Hubble has spotted a few interesting asteroid behaviors recently. You may recall in November the telescope spotted an asteroid, designated P/2013 P5, with six comet-like tails of dust radiating from it like spokes on a wheel or a spinning garden sprinkler.
"We were literally dumbfounded when we saw it," said lead investigator David Jewitt of the University of California at Los Angeles in a statement. "Even more amazing, its tail structures change dramatically in just 13 days as it belches out dust. That also caught us by surprise. It's hard to believe we're looking at an asteroid."
Modeling by team member Jessica Agarwal of the Max Planck Institute for Solar System Research in Lindau, Germany, showed that the tails could have been formed by a series of what are known as impulsive dust-ejection events . Radiation pressure from the Sun smears out the dust into streamers. "Given our observations and modeling, we infer that P/2013 P5 might be losing dust as it rotates at high speed," says Agarwal in a statement. "The Sun then drags this dust into the distinct tails we're seeing."
P/2013 P5 has been ejecting dust periodically for at least five months. Astronomers believe it is possible the asteroid's rotation rate increased to the point where its surface started flying apart.
It appears P/2013 P5 is a fragment of a larger asteroid that broke apart in a collision roughly 200 million years ago. There are many collision fragments in orbits similar to P/2013 P5's. Meteorites from these bodies show evidence of having been heated to as much as 1,500 degrees Fahrenheit. This means the asteroid likely is composed of metamorphic rocks and does not hold any ice as a comet does, Jewitt stated.
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