Mysterious object Oumuamua arrived in our solar system in October 2017 

NASA spotted unexpected boost in speed and shift in trajectory as it passed through the inner solar system last year

Now one study claims it could actually be a solar sail sent by aliens 

A mysterious asteroid called Oumuamua, the first interstellar object ever seen in the solar system, could be a gigantic alien solar sail send to look for signs of life, a new study has claimed. 

Astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) analyzed the strange cigar shape of the object, and an unexpected boost in speed and shift in trajectory as it passed through the inner solar system last year.