Astronomers reveal that the mysterious asteroid Oumuamua spins uncontrollably. And it's done for at least another billion years.
"At some point there has been a collision," said Queen's University astronomer Dr. Wes Fraser on the BBC's Sky At Night show after his research was published in Nature Astronomy, as reported today news.com.
This British-based researcher has broken the light pattern reflected from the unusual object.
This object has previously been set to have a length of 200m. At eight times the size of the width, this object is roughly shaped like a crumpled cigar.
Initially Oumuamua is estimated to rotate every seven or eight hours. But that does not seem right.
The variation of the dull reddish light reflected from the surface of this distant object can reveal how it moves. Apparently, it does not move in the usual pattern.
This object does not rotate quietly along its axis like most asteroids. This object moves in chaos. And it may have been done for hundreds of millions of years.
"The movement actually causes internal stress and tension on the object, and it slowly but surely squeezes and pulls the object like a tidal on Earth to remove energy from that spin," said Dr. Fraser.
This torque has changed the object for thousands of years. In the end it will absorb all the spin energy, and cause it to slide gently through outer space. But it will take about a billion years.
This fact also shows that Oumuamua is quite dense, as a rock or metal lump. Otherwise, it will be fragmented, or absorb the rotation long before now.
Then what causes a spin? "It's hard to know whether it's round during formation of a planet or after the planet-forming process," said Dr. Frazer. "Of course, more collisions occur as the planet grows than after."
"But unfortunately we can not get a high resolution image of this thing to see what kind of crater above it might be attributed to the collision. "
Interstellar winds, heat radiation, encounters with planets can all contribute to its very exciting and almost eternal movement.
Oumuamua has sparked a revolution for astronomy. It is the first known object that enters our Solar System from deep space (the deep space from Earth).
While there are actually more than a thousand similar interstellar asteroids captured by the gravitational pull of our Sun, we do not see them coming.
But astronomers are not sure what Oumuamua is. It's like a rocky asteroid. It does not flare like a comet as it passes very close to the Sun (37 million kilometers) last year.
Oumuamua itself will not last long in our Solar System. At its current pace, it will pass through Jupiter in May and Saturn early next year. It will not be long until we leave our Solar System.
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