Mysterious interstellar 'Oumuamua' object could be a solar-powered alien probe, Harvard scientists say

ESA/Hubble; NASA; ESO; M. Kornmesser

An artist's depiction of interstellar object 'Oumuamua, which astronomers believe is a comet (not an asteroid).

• Harvard scientists have raised the possibility that a mysterious cigar-shaped interstellar object, the first of its kind ever found in our solar system, could have come from an alien civilization.
• The scientists sought to explain quirks in Oumuamua's movement by calculating whether it could be powered by the sun's radiation.
• Nobody knows what Oumuamua is or where it came from, and it's too late to find out for sure.

Harvard scientists have raised the possibility that a mysterious cigar-shaped interstellar object, the first of its kind ever found in our solar system, could be a probe intentionally sent towards Earth from an alien civilization.

A Hawaiian telescope first spotted 'Oumuamua - meaning "a messenger from afar, arriving first" in Hawaiian - in October 2017. The metal-rich object was found to be about 750 feet by 115 feet in size and reddish in color. It was moving inexplicably fast but not circling the sun.

Instead, it had dived between Mercury and the sun and was zooming past Earth on its way out of our solar system. This path meant that 'Oumuamua was an interstellar traveler from beyond the solar system. Scientists first called the object an asteroid, then later deemed it a mildly active comet. But 'Oumuamua didn't show the typical signs of a comet, like a tail of dust and gas.

Just in case, astronomers pointed powerful radio telescopes at the object to scan for radio transmissions. But they found nothing.

Since 'Oumuamua's discovery, however, scientists have continued to wonder whether it could have originated from some intelligent life-form.

A new paper from Harvard scientists Shmuel Bialy and Abraham Loeb suggests that quirks in Oumuamua's rotation and speed could be the result of solar-powered movement. That means the object would be made of some thin material that could absorb radiation from the sun - either a naturally created material that we've never seen before, or something made by aliens.

'Oumuamua "might be a lightsail of artificial origin," the paper states, referring to an object designed to use solar radiation for propulsion. Humans have experimented before with lightsails, but the idea remains in its infancy.

"One possibility is that 'Oumuamua is a lightsail, floating in interstellar space as a debris from an advanced technological equipment," the paper states.

The idea that the object could have been part of some massive alien solar-powered technology may seem far-fetched, but the authors go on to suggest an even more "exotic" explanation.

"Alternatively, a more exotic scenario is that 'Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization," the paper states.

The authors argue that if 'Oumuamua is just a random interstellar rock, we should have seen more objects like it. That fact, combined with the object's strange movements, suggest it could have its own source of power beyond gravitational pulls, the authors suggest.

'Oumuamua has already passed Earth on its way out of the solar system, so the object is too far away for scientists to continue studying it. That means the origin, behavior, and makeup of 'Oumuamua will remain a mystery. So the Harvard authors' "exotic" guesses are just as good as anyone's at this point.

Loeb told NBC News that his idea that 'Oumuamua could be alien-made was "purely scientific and evidence-based."

"I follow the maxim of Sherlock Holmes: When you have excluded the impossible, whatever remains, however improbable, must be the truth," Loeb said.