Three potentially habitable planets orbiting an ultracool dwarf star about 39 light years from Earth have opened up a new "hunting ground" in the search for alien life.
The trio of Earth-like planets are similar in size to our home and are close enough for their atmospheres to be analysed with technology we already have, scientists said.
"This is the first opportunity to find chemical traces of life outside our solar system," Michael Gillon, an astrophysicist at the University of Liege in Belgium, said.
Using a 60cm telescope in Chile, known as TRAPPIST, scientists tracked several dozen dwarf stars not visible with optical telescopes.
After identifying the most promising one, which is about one-eight of the size of the Sun and observing it for several months, scientists noticed its infrared signal faded slightly at regular intervals, suggesting it had objects orbiting it.
The study concluded their size and proximity to the star meant all three planets could have regions at temperatures within a range suitable for sustaining liquid water and life.
Julien de Wit, from the Massachusetts Institute of Technology (MIT), said the team had hit the "jackpot".
"These planets are so close, and their star so small, we can study their atmosphere and composition," he said.
He added that it could be determined if they are home to life "within our generation".
For life as we know it to exist, planets have to be in a "Goldilocks zone" in relation to their star, far enough away so that its heat does not evaporate all the water, but close enough so that it can exist in liquid form.
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