Lost ‘alien’ asteroid observed by astronomers
A LOST asteroid shaped like a cigar has entered our solar system after wandering between the stars for hundreds of millions of years, scientists say.
The dark red rock named Oumuamua, which in Hawaiian means messenger, is about 1,312 ft long and highly-elongate - perhaps 10 times as long as it is wide, according to a study reported in Nature journal, reports The Sun.
It is the first space rock from outside the solar system ever observed by astronomers.
A telescope in Hawaii designed to spot Near-Earth Objects (NEOs) picked up the asteroid on October 19 as a faint point of light moving across the sky.
After further observations and orbital calculations, scientists reported there was no beyond doubt that the object originated from outside the solar system.
Moving at 95,000 kilometres per hour, Oumuamua was at first thought to have travelled from the bright star Vega, 25 light years away in the northern constellation of Lyra.
But Vega was not even close to its present position 300,000 years ago, when its journey would have started.
That has led scientists to speculate that the asteroid is an interstellar wanderer that has stumbled across our solar system.
Dr Karen Meech, from the Institute for Astronomy in Hawaii, said: "Oumuamua may well have been wandering through the Milky Way, unattached to any star system, for hundreds of millions of years before its chance encounter with the solar system."
"This unusually large variation in brightness means that the object is highly elongate: about 10 times as long as it is wide, with a complex, convoluted shape.
"We also found that it has a dark red colour, similar to objects in the outer solar system, and confirmed that it is completely inert, without the faintest hint of dust around it."
The asteroid's properties suggest it could have a high metal content and lacks significant amounts of water or ice.
Its surface has been darkened and reddened by the impact of cosmic rays over millions of years.
Astronomers estimate that interstellar asteroids pass through the inner solar system about once a year, but they are faint and hard to spot.
Oumuamua was discovered by the 1.8 metre Pan-STARR telescope in Hawaii, which is part of a system set up to track potentially threatening NEOs.