An artist's illustration of the seven TRAPPIST-1 planets, in their respective orbits. (NASA-JPL/Caltech)
The seven worlds are orbiting the small, cool star some 40 light-years away.
All of the planets are similar to Earth in terms of mass and size.
Three of the planets reside in the “habitable zone” around their star.
According to NASA, liquid water may exist on their surfaces—though follow-up observations are needed to be sure.
"It is very promising for the search for life outside our solar system," said researcher Michael Gillon.