Three habitable worlds orbiting around a nearby ultracool dwarf star could be the best bet of finding life on another planet.
The three Earth-like "red worlds" are just 40 light years away from Earth.
The sizes and temperatures of these worlds are comparable to those of Earth and Venus, and are the best targets found so far in the search for life outside the solar system.
Scientists believe they may teem with life forms adapted to infrared worlds, and there could be other as yet undiscovered worlds out there too.
TRAPPIST-1 is much cooler and redder than the Sun and barely larger than Jupiter, but such stars are both very common in the Milky Way and very long-lived.
It lies in the constellation of Aquarius (The Water Carrier).
And because the planets are so close, astronomers should eventually be able to study in greater detail the composition of each of the planets and their atmospheres, as well as look for chemical signals of life.

Professor of physics Adam Burgasser at theUniversity of California, San Diego said: "The kind of planets we've found are very exciting from the perspective of searching for life in the universe beyond Earth.
"While such a 'cold' star might sound exotic, many, if not most, of the stars in our Milky Way Galaxy are of this cool, red, small and dim variety.
"If Earth-like planets around these stars turn out to be common, there may be many more habitable planets out there than current estimates predict."
The international team used the TRAPPIST telescope based in Chile to observe the star 2MASS J23062928-0502285, now known as TRAPPIST-1.
They found this dim and cool star faded slightly at regular intervals, indicating that several objects were passing between the star and the Earth and detailed analysis showed three planets with similar sizes to the Earth were present.