Illustration of Oumuamua. In 2017, astronomers discovered an object in the Solar System which seemed out of place. Its orbit is highly hyperbolic, not parabolic, which implies it originated outside of the Solar System and is just passing through. The interloper has been named Oumuamua ??Hawaiian for scout or messenger. Follow-up observations have revealed that Oumuamua is very oddly shaped, like a cigar, more elongated than any known Solar System object. Estimates put its size at 200 x 30 x 30 m, and its rotational period at 8.14 hours. An alternative possibility, however unlikely, has been mentioned in a scientific paper - that the object might actually be an alien spacecraft such as a solar sail (left).