Many images from deep space are so cool, weird and unusual it is hard to believe they are real sometimes. This is one of them.
Astronomers looking deep into the asteroid belt through NASA's Hubble Space Telescope say they have 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."
One explanation for the odd appearance is that the asteroid's rotation rate increased to the point where its surface started flying apart, ejecting dust in episodic eruptions that started last spring, the researchers stated. The scientists ruled out an asteroid impact because they said a lot of dust would have been blasted into space all at once, whereas P5 has ejected dust intermittently over a period of at least five months.
Careful 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.
"In astronomy, where you find one, you eventually find a whole bunch more," Jewitt said. "This is just an amazing object to us, and almost certainly the first of many more to come."
Hubble has seen its share of weird asteroid shapes. In 2010, Hubble spotted a strange X-shaped asteroid. However, unlike P/2013 P5, this was thought to have been formed by a collision, researchers said. Also in 2010 astronomers observed asteroid Scheila, an object with a tail that was surrounded by a C-shaped cloud of dust. This asteroid was also thought to be the result of a collision between Scheila and a much smaller body -- only the second time that such an event has been spotted.