A cigar-shaped asteroid flying through space in our direction could be a huge alien solar sail on a mission to find signs of life, scientists claim.

Astronomers from the Harvard Smithsonian Center for Astrophysics (CfA) have detected an unexpected boost in speed and shift in trajectory in the red object named Oumuamua as it passed through the inner solar system.

The change in course and speed was so pronounced, they concluded it “might be a lightsail of artificial origin.”

Constantly streaming solar particles, called photons, could be harnessed in huge sails in the same way wind is on Earth.

The research paper said: “Considering an artificial origin, one possibility is that Oumuamua is a lightsail, floating in interstellar space as a debris from an advanced technological equipment.

“Alternatively, a more exotic scenario is that Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization.”

Theoretical physicist Avi Loeb Loeb told Universe Today: “Oumuamua could be an active piece of alien technology that came to explore our solar system, the same way we hope to explore Alpha Centauri using Starshot and similar technologies.”

“The alternative is to imagine that Oumuamua was on a reconnaissance mission.”

Before he died in March, Professor Stephen Hawking said: “Researchers working on long-distance space transportation have previously suggested that a cigar or needle shape is the most likely architecture for an interstellar spacecraft, since this would minimize friction and damage from interstellar gas and dust.”