Tabby’s Star fluctuates in brightness so much, and at such irregular intervals, that scientists can not work out what causes it.
KIC 8462852, also known as Tabby’s Star, has been monitored for several years after it was noticed that its brightness changed significantly and at irregular intervals.
A range of theories have been put forward for this strange behaviour, including one hypothesis which suggests an alien megastructure may have been built around the star to harvest its energy.
Although the star was first discovered in the 1890s, it was not until observations between 2009 and 2013 when scientists first noticed something particularly odd about it.
It was subsequently named after Louisiana-based astronomer Tabetha Boyajian, who wrote a paper about its strange behaviour.
Professor Boyajian noticed that at one point Tabby’s Star’s brightness had dropped by 22%, which can not be explained by any properly understood phenomenon.
Last month scientists noticed what appeared to be another slight dimming of the star – but that accelerated significantly on Friday, causing a scramble for additional observations.
Jason Wright, associate professor of astronomy and astrophysics at Penn State University, told a web chat: „One of the difficulties here is that most telescopes are scheduled weeks, months in advance.
„We can’t just jump on a telescope and take a spectrum typically. So we need to have a network of people around the world.“
Tabby’s Star is in the constellation Cygnus and is approximately 1,275 light years from Earth.
Scientists hope they might be able to work out what is causing the star to dim by analysing its full spectrum of light. But to do this, they need to know when that dimming is going to occur.
Astronomers do not believe it is being caused by a planet passing in front the star as this would not cause such a significant change in brightness, and it would be more predictable.
A number of other theories have been put forward. One suggests there may be a large cloud of dust and debris around the star.
Another suggestion is that it is recovering having been hit by a planet and a third theory suggests a swarm of comets may be responsible.
The most unusual suggestion – but one which scientists can not yet dismiss – is that an alien megastructure has been built around the star to harvest its energy.
The concept, which sounds like it comes straight out of science fiction, is actually referred to as Dyson Sphere.
It is named after British-born scientist Freeman Dyson who, in the 1960s, hypothesised that advance civilisations would seek to power their worlds in this way.
