Astronomers confirm mysterious object seen last month originated from different solar system
22 November 2017
Astronomers have confirmed that the mysterious object detected hurtling past our sun last month is indeed from another solar system. 1I/2017 U1('Oumuamua) as it has been named, could have originated from 10,000 other solar systems lurking undetected in our cosmic neighbourhood.
An analysis of its orbit has shown that its orbit is almost impossible to achieve from within our solar system. The name of the object is derived from a Hawaiian term for messenger or scout and it is the first space rock to have been identified as forming around another star. According to experts, since asteroids coalesce during the process of planet formation, this object could tell us something about the formation of planets around its unknown parent star.
Analyses using ground-based telescopes have shown that 'Oumuamua is quite similar to some comets and asteroids in our own solar system, which is important as it suggests that planetary compositions like ours could be typical across the galaxy.
The object is thought to be extremely dark as it absorbs 96 per cent of the light that falls on its surface, and it is red. This colour is the hallmark of organic (carbon-based) molecules, the building blocks of the biological molecules that allow life to function.
According to astronomers, the results of their observations suggest that it is at least 10 times longer than it is wide. They say the ratio is more extreme than that of any asteroid or comet ever observed in our Solar System.
According to Karen Meech, from the Institute for Astronomy in Honolulu, Hawaii, and colleagues, who used observations from the Very Large Telescope in Chile, the object is about 400m long, rapidly rotating and subject to dramatic changes in brightness.
These changes in brightness provided clues to 'Oumuamua's bizarre shape.
"Looking at the asteroid light curve database, there are five objects (out of 20,000) that have light curves that would suggest a shape up to an axis ratio of about 7-8 to 1," Dr Meech told BBC News.
"Our errors are very small, so we are confident this is really elongated. Also, one has to realise we don't know where the rotation pole is pointed. We assumed that it was perpendicular to the line of sight. If it were tipped over at all, then there are projection effects and the 10:1 is a minimum. It could be more elongated!"