Mysterious 'alien megastructure' causes dimming of Tabby's Star

The mystery of why a distant star keeps dimming continues to baffle scientists, fueling rumors that it is being orbited by an "alien megastructure". Astronomers have once again detected unusual light patterns coming from a star called KIC 8462852 - or Tabby's Star.

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They are excited because this presents an extraordinary opportunity to observe whatever it is passing in front if it.

According to a report in The Atlantic , astronomers plan to take "spectra" from the dimming star, which will tell them what material the orbiting object is made of. 

This will help them determine whether it is natural, or has a technological origin - indicating it has been built by an advanced, spacefaring civilization.

The astronomical world lit up in 2011, after planet spotters noticed an unusual light pattern emanating from the star, which sits some 1,480 light years from Earth.

At first it was though the dimming was caused by a swarm of objects orbiting the star , such as comets or shrapnel from an asteroid impact. 

However, astronomer Jason Wright from Penn State University offered a more unusual explanation - that the strange light pattern was caused by an "alien megastructure" harvesting energy from the star. 
While the alien megastructure theory might sound crazy, further observations by scientists have ruled out many of the more natural explanations. 

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A recent paper by Ben Montet of Caltech and Joshua Simon of the Carnegie Institute, claims that the pattern of dimming is not consistent with comets or any other type of naturally-occurring space debris.

The astronomers used Kepler to study the luminosity of the star, and found that it dipped by about 0.34% per year during the first 1,000 days of observations, then dipped by more than 2% over the course of the next 200 days.

That makes three patterns of dimming - the long-term decline, the 200-day dip, and the deep drops that made Tabby's Star famous in the first place.
"We can come up with scenarios that explain one or maybe two of these, but there’s nothing that nicely explains all three," Montet told New Scientist .
It could be that multiple phenomena are coming together to cause different aspects of the dimming - or it could be aliens after all. One thing we know for sure is that more data is needed.

Several telescopes around the world regularly track the star, and data from Kepler has been made available to the public through a program called Planet Hunters, encouraging "citizen scientists" to help solve the mystery.

It is hoped that these observations could be used to test different hypotheses about the cause of the dimming - an ultimately find an answer.