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TRAPPIST-1 habitable zone compared to our Solar System

TRAPPIST-1 habitable zone compared to our Solar System
TRAPPIST-1 habitable zone compared to our Solar System The red dwarf star TRAPPIST-1 has seven known Earth-sized planets closer to their star than Mercury is to our Sun. Our Sun is too hot for liquid water to exist on the surface at that distance. But TRAPPIST-1 is a cooler red dwarf star, placing exoplanets e, f, and g in the habitable zone—the not-too-hot, not-too-cold region where surface water can exist. The habitable zones of both star systems are shown in green. NASA / JPL-Caltech