Illustration of a spacecraft visiting the asteroid 1I/2017 U1 ('Oumuamua), discovered in October 2017. This asteroid is the first to be confirmed as originating around another star. It came from the direction of the star Vega, which is 25 light years from the Sun. 'Oumuamua measures up to 400 metres long and is thought to be 10 times as long as it is wide, the first time an asteroid of this shape has been observed. It also has the largest variation in brightness as it spins about its axis ever observed.