INTERSTELLAR ASTEROID CAPTURED ENTERING THE SOLAR SYSTEM
An oddly shaped asteroid has entered the Solar System, and is the first confirmed object from another star. Officially dubbed 1I/2017 U1, but known as `Oumuamua (`Oumuamua comes from the Hawaiian word for ‘scout’), the space rock was captured by the Pan-STARRS 1 telescope in Hawaii. First thought to be a comet thanks to its trajectory and high speed, `Oumuamua had already passed its closest to the Sun when it was detected, so the race was on to gather as much data as possible. At New Year, the asteroid was roughly three times the distance of the Earth from the Sun and is currently speeding away from our planet at 90,000km/h.
Telescopes can’t get a good picture of `Oumuamua, but astronomers managed to determine its shape from variations in the brightness readings as the asteroid spins once every 7.3 hours.
“This unusually large variation in brightness means that the object is highly elongated: about 10 times as long as it is wide, with a complex, convoluted shape,” said researcher Karen Meech. “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.”
`Oumuamua appears to have come from the direction of Vega, a bright star about 25 lightyears away. It’s estimated that such visitors arrive roughly once every year.
“We are continuing to observe this unique object,” said researcher Olivier Hainaut, “We hope to more accurately pin down where it came from and where it is going next on its tour of the Galaxy. And now that we have found the first interstellar rock, we are getting ready for the next ones!”
INSET: `Oumuamua (marked by blue circle) photographed through telescopes
MAIN IMAGE: Artist’s impression of the elongated asteroid named `Oumuamua