Seven Earth-sized Exoplanets Found

The system of planets found orbiting nearby dwarf star TRAPPIST-1 may be our best chance yet of finding alien life

TRAPPIST-1, an ultra cool dwarf star located just 40 light-years from Earth in the Aquarius constellation, was first detected by researchers from Liege using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, and later confirmed by NASA’s Spitzer Space Telescope and the Very Large Telescope, also in Chile.The planets were detected by observing dips in the star’s light output caused by each of the seven planets passing in front of it, events known as transits. The researchers found that all of the planets are comparable in size to the Earth, while density measurements suggest that the innermost six are rocky.

Current climate models suggest the three innermost planets are probably too hot to support liquid water, and the one furthest from the star is too cold. However, the remaining three sit comfortably within the habitable zone and could host oceans of surface water – a feature thought to be essential for the existence of life.

“The energy output from dwarf stars like TRAPPIST-1 is much weaker than that of our Sun. Planets would need to be in far closer orbits than we see in the Solar System if there is to be surface water,” said researcher Dr Amaury Triaud. “Fortunately, it seems that this kind of compact configuration is just what we see around TRAPPIST-1.”