Is it a comet or an asteroid? Hubble spots a six-tailed rock spinning in space - and experts have been left ‘dumbfounded’

The entire structure rotates like a bicycle wheel with spokes on one side

Astronomers believe the tails formed when its rotation rate increased

This may have caused its surface to fly apart leaving streams of dust



It takes a lot to shock an astronomer - but this recent discovery has left Hubble researchers ‘literally dumbfounded’.

It what they can only describe as a ‘weird and freakish’ sighting, scientists have found what looks like a cosmic sprinkler in space.

The mysterious celestial object is in fact an asteroid, P/2013 P5, which has six comet-like tails of dust radiating from it like spokes on a wheel.

This is a diagram of the structure seen around the six-tailed asteroid named P/2013 P5. Normal asteroids should appear simply as tiny points of light

Normal asteroids should appear simply as tiny points of light and nothing like this has ever been seen before.

Even more amazing is the asteroid's tail structure, which changed dramatically in just 13 days.

‘That also caught us by surprise. It's hard to believe we're looking at an asteroid,’ said lead investigator David Jewitt of the University of California.

Astronomers are now scratching their heads to find an adequate explanation for its out-of-this-world appearance.

The multiple tails were discovered in Hubble images taken on September 10, 2013. When Hubble returned to the asteroid on September 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around

A MEMBER OF THE FLORA FAMILY

The orbit of the asteroid could make it a member of the Flora asteroid family. This means that it is probably a piece from an asteroid collision that occurred roughly 200 million years ago. The resulting collision fragments are still following similar orbits. Meteorites from these bodies show evidence of having been heated to as much as 8315 degrees C. This means the asteroid is likely made of metamorphic rocks and so is not capable of holding ices as comets do.

One theory is that the tails formed through a series of impulsive dust-ejection events.

These could have been triggered when the nudge of sunlight spun up the asteroid to the point where dust is falling off the surface and into space.

The team has ruled out a recent asteroid impact scenario because a lot of dust would be blasted into space all at once, whereas P5 has ejected dust for at least five months.

‘The protracted period of dust release appears inconsistent with an impact origin, but may be compatible with a body that is losing mass through a rotational instability,’ they wrote in their report.

The asteroid was discovered as an unusually fuzzy-looking object with the Pan-STARRS survey telescope in Hawaii.

The multiple tails were discovered in Hubble images taken on September 10. When Hubble returned to the asteroid on September 23, its appearance had totally changed.

It looked as if the entire structure had swung around.

‘We were completely knocked out,’ Professor Jewitt said.

Astronomers are still scratching their heads to find an adequate explanation for its out-of-this-world appearance, which was discovered by Hubble (pictured)

The orbit of the asteroid could make it a member of the Flora asteroid family.

This means that it is probably a piece from an asteroid collision that occurred roughly 200 million years ago.

If the asteroid's spin rate became fast enough, Professor Jewitt said, the asteroid's weak gravity would no longer be able to hold it together.

Dust might avalanche downslope towards the equator, and maybe shatter and fall off, eventually drifting into space to make a tail.

So far, only a small fraction of the main mass - around 100 to 1,000 tonnes of dust - has been lost.

The 700-foot-radius nucleus is thousands of times bigger.

Professor Jewitt's interpretation implies that rotational breakup must be a common phenomenon in the asteroid belt; it may even be the main way in which small asteroids die.

‘In astronomy, where you find one, you eventually find a whole bunch more,’ he said.