One of Australia's leading experts on NASA's Kepler Space Telescope says variations in the telescope itself could be the reason for the unexplained behaviour of star KIC 8462852.

The star has baffled the world's leading scientists by displaying large and erratic dips in brightness, far greater than is normally seen from stars orbited by planets.

Even a planet the size of Jupiter would only cause dimming of approximately 1 per cent, but the star was observed to dim by up to 22 per cent.

The story got even weirder this year when two separate studies reported that the perplexing celestial object has been steadily darkening over time — also not normal star behaviour.

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The most common form of alien mega-structure concept is a Dyson Sphere A Dyson Sphere is a hypothetical structure that completely encompasses a star and captures its power output

A Dyson Sphere is a hypothetical structure that completely encompasses a star and captures its power output Physicist and astronomer Freeman J Dyson first explored this idea as a thought experiment in 1960

Physicist and astronomer Freeman J Dyson first explored this idea as a thought experiment in 1960 He proposed searching for evidence of the existence of such structures might lead to the discovery of advanced civilizations

Without a natural explanation, even the world's most reputable astrophysicists have been forced to consider the possibility of an alien-built mega-structure — a 'last resort' hypothesis put forward by Penn State University's Jason Wright.

"If there were alien civilisations that build massive structures around their stars — as some people have hypothesised — Kepler would discover them and they would look something like the dips that we saw around Tabby's star," he told Catalyst.

"The problem with this hypothesis is that it is very hard to test. We don't know what an alien mega-structure would look like so there is really nothing we can do to show that's what it is or isn't."

Could interference in the data explain the dips?

The Kepler telescope is NASA's premier planet hunter, but Australian National University's research fellow Dr Brad Tucker uses it to look for supernovas and black holes, as a lead on the Kepler Extra-Galactic Survey (KEGS) project.

The mysterious star sits in the patch of sky in the direction of the constellations Cygnus and Lyrae. ( Supplied )

The cosmologist said he has seen similar features to the star in the Kepler data whilst looking for supernovas.

"When most people have used Kepler, they've been looking at very bright things that are only in one very small area of the Kepler image," he told Catalyst.

"But I've been using Kepler to find exploding stars and understanding how black holes work and because galaxies are big, they require looking at multiple pixels, multiple parts of the Kepler image."

Dr Tucker said Kepler was designed so that a star only would appear on one pixel in the Kepler image so that they didn't have to account for problems that could happen naturally.

"But let's say if the star happens to slightly vary on two, then that can create some artificial measurements," he said.

"If it keeps shifting that way over time that would cause this pixel to look dimmer over time.

"We also know Kepler moves around as it orbits around the sun, we know sometimes it shifts its measurements where on the camera it takes place."

The astronomer who first looked at the data, Dr Tabetha Boyajian, after whom the star is nicknamed "Tabby's star", said her first instinct was to think the light flux was due to a problem with the data too.



"But there were several independent checks with the data so we're pretty confident that this is something that is happening in space whether it is with the star itself or something between us and the star," she said.

The data has been examined by many astronomers since the initial findings were published, including the Kepler team at NASA.

At first astronomers considered the dips in the stars light might be due to a family of comets, but since then have discovered there is no infra-red evidence. ( Supplied/NASA Jet Propulsion Laboratory )

"I don't discount the literally hundreds of other people that have thought about this but for at least my own understanding, I want to make sure I'm confident that this really is an awesome star," Dr Tucker said.

Dr Boyajian and Professor Wright have crowdsourced money for time on the Las Cumbres Observatory Global Telescope Network in the hope of catching the star's unusual light dips in action and gathering more data on it.

They will also point the world's largest steerable radio telescope at Green Bank at the star in a couple of weeks' time to see if they are any strange signals that might be evidence of extra terrestrials.

A previous look for laser signals by the Search for Extra Terrestrial Intelligence (SETI) International organisation found no evidence of an alien civilisation.

"It is the best target we have for efforts to search for signals from extra-terrestrial intelligence," Professor Wright said.

"So while we are busy ruling out these natural hypotheses we also going to point radio telescopes at Tabby's star — just in case."

Despite his research, Dr Tucker is not against the alien mega-structure theory.

"I think maybe some people feel that they don't want it to be aliens. I would love it if it was aliens!" he said.

"But unfortunately I think that it's, to some degree, a natural problem with Kepler."