The first asteroid observed visiting our Solar System from elsewhere has travelled for millions of years.
First spotted on October 19, 2017, by the Pan-STARRS 1 telescope in Hawaii, Oumuamua is about 400 meters long, its length being 10 times greater than its width.
Unlike any other asteroid we’ve seen before, it is bizzare cigar-shaped and it’s spinning on its axis once every 7.3 hours.
“What we found was a rapidly rotating object, at least the size of a football field, that changed in brightness quite dramatically. This change in brightness hints that `Oumuamua could be more than 10 times longer than it is wide – something which has never been seen in our own Solar System.” said Karen Meech from University of Hawaii’s Institute for Astronomy (IfA)
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A composite image of `Oumuamua, which is the white dot in the middle. ESO/K. Meech et al.
“This unusually big variation in brightness means that the object is highly elongated: about ten times as long as it is wide, with a complex, convoluted shape. We also found that it had a reddish color, similar to objects in the outer Solar System, and confirmed that it is completely inert, without the faintest hint of dust around it,” said Karen Meech from the Institute for Astronomy in Hawaii.
Oumuamua was forcefully accelerated by the Sun’s gravity on 9 September, at a speed of 315,000 kilometres per hour (196,000 miles per hour). The asteroid made of dense material (no water or ice) is going to pass Jupiter’s orbit in May 2018 and Saturn’s in January 2019.
Animation of `Oumuamua passing through the Solar System
This animation (annotated) shows the path of the interstellar asteroid 1I/2017 (`Oumuamua) through the Solar System. Observations with ESO’s Very Large Telescope and others have shown that this unique object is dark, reddish in colour and highly elongated.
The path of Oumuamua in our Solar System. Credit: ESO/K. Meech et al