Astronomers have detected a record seven Earth-sized planets orbiting a single star.

The researchers say that all seven could potentially support liquid water on the surface, depending on the other properties of those planets. However, three of these worlds are within the "habitable" zone where life is considered a possibility. The compact system of exoplanets orbits Trappist-1, a low-mass, cool star located 40 light-years away from Earth. The planets were detected using Nasa's Spitzer Space Telescope and several ground-based observatories are described in the journal Nature. Read more