Mysterious interstellar cigar-shaped asteroid Oumuamua had a violent past, research reveals

The first-ever interstellar cigar-shaped asteroid dubbed Oumuamua had collided with something strange in the space before it entered our solar system, a scientist from the Queen's University Belfast has claimed.

Dr Wes Fraser also believes that Oumuamua had a violent past, which resulted in the space rock spinning or tumbling chaotically for billions of years.

Quite a stir was created when this alien asteroid was first spotted by astronomers. It was initially believed to be a comet but was later reclassified as an asteroid.

Speculations were even made that the space rock was a UFO. A scientific body led by Stephen Hawking is also trying to decipher whether it is an alien probe or a previously unseen natural phenomenon.

Yuri Milner, a Russian billionaire and physicist who is behind the largest-ever scientific research programme called Breakthrough Listen, which aims at finding proof of civilizations beyond Earth. The research had speculated the possibility about conspiracy theory behind asteroid Oumuamua transmitting radio signals to be true, but these conspiracy theories turned out to be false.

Dr Wes Fraser has analysed the asteroid and found that it was not spinning periodically like most of the small celestial bodies and space rocks in our solar system. It is being believed that another asteroid had hit Oumuamua before it was violently thrown out of its system to the interstellar space.

"Our modelling of this body suggests the tumbling will last for many billions of years to hundreds of billions of years before internal stresses cause it to rotate normally again," Dr Fraser said.

"While we don't know the cause of the tumbling, we predict that it was most likely sent tumbling by an impact with another planetesimal in its system before it was ejected into interstellar space," he added.

The asteroid is 400 metres (a quarter mile) long, rocky and has a reddish hue. And the color differs between measurements, which has also left the astronomers baffled.

Dr Fraser's research has brought to light that the surface of the space rock is spotty. The asteroid appeared to be mostly red in color when it was facing Earth-based telescopes, but the remaining part of the body appeared to be neutral-colored like dirty snow.

"Most of the surface reflects neutrally but one of its long faces has a large red region. This argues for broad compositional variations, which is unusual for such a small body," Dr Fraser said.

"We now know that beyond its unusual elongated shape, this space cucumber had origins around another star, has had a violent past and tumbles chaotically because of it. Our results are really helping to paint a complete picture of this strange interstellar interloper. It is quite unusual compared to most asteroids and comets we see in our own solar system," he concluded.