Advanced alien technology is one explanation for the weird light pattern coming from a distrant star.

The technique used to find planets far off in space has thrown up a bizarre discovery that some scientists speculate could be caused by alien megastructures.

The Kepler Space Telescope found a significant amount of light from the weird star is being blocked.

One theory is that a sea of comets is circling the star, but that would be extremely unlikely.

Another theory is that megastructures have been placed in orbit, perhaps solar collectors catching energy from the star. Such hypothetical structures are known as Dyson swarms or spheres.

The weird star was the only one of 150,000 stars watched over four years to behave the way it does.

Kepler was looking for tiny dips in the amount of light emitted by the stars. The dips can be shadows cast by orbiting planets. Normally, they happen regularly and for a few days at most.

But the light from KIC 8462852, 1480 light years away, darkens at irregular intervals by as much as 20 per cent and can stay dark for up to 80 days.

READ MORE:

* Stephen Hawking launches search for aliens

* Finding aliens and the meaning of life

"We'd never seen anything like this star," Yale University post doctorate student Tabetha Boyajian told The Atlantic. "It was really weird. We thought it might be bad data or movement on the spacecraft, but everything checked out."

Boyajian oversees the Planet Hunters group of "citizen scientists" set up by Kepler astronomers to examine light patterns from the stars watched by the telescope.

Several of the citizen scientists flagged the weird star, and some are co-authors of a paper written by Boyajian, exploring scenarios that might explain its light pattern.

The only natural explanation considered possible is the circling comets theory, in which the comets were yanked into orbit from a passing star.

Penn State astronomer Jason Wright told Popular Science the comet hypothesis was a bit contrived but it was possible Kepler had caught a rare event.

"It's hard to imagine how comets could block that much light. You need a huge number of them, and we must have caught them at a time when they happened to be all clumped together."

Wright and his co-authors are about to publish a theory that the unusual star's light pattern is consistent with a "swarm of megastructures".

"Aliens should always be the very last hypothesis you consider, but this looked like something you would expect an alien civilisation to build," Wright told The Atlantic.

Wright, Boyajian and Andrew Siemion, director of the SETI Research Centre at the University of California, Berkeley are writing up a proposal to point a massive radio dish at the unusual star. They want to see if the star emits radio waves at frequencies associated with technological activity.

"If we hear narrow-band modulated radio emissions coming from that star, I can't imagine any other explanation," Wright told Popular Science. "Nature doesn't do that, it would have to be artificial."

That would tell them if the radio waves are coming from the general area of the star. If they are, the next step would by to try to tune in with the Very Large Array in New Mexico, which could find out if the waves are coming specifically from the strange star.