A few of the planets orbiting a star called TRAPPIST-1, which is 40 light years away, have shown another sign they might be right for life: water. A team of researchers using the Hubble Space Telescope have found hints of this key component for life at three of the seven worlds.
These three exoplanets orbit in the star’s habitable zone, the narrow corridor where temperatures are mild enough to permit liquid lakes and oceans that don’t boil away or freeze.
TRAPPIST-1 may be small and dim, but dwarf stars like it often emit powerful flares of radiation that could make water and life on its planets impossible without thick protective atmospheres.
Vincent Bourrier at the University of Geneva in Switzerland and his colleagues tracked the UV radiation that reaches TRAPPIST-1’s planets. If there were too much UV light, no water could survive on the surface because the water molecules would break up and escape through the top of the atmosphere as hydrogen and oxygen gas.
But, for a handful of the planets around TRAPPIST-1, there’s not enough UV radiation to destroy the water molecules.
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