Habitable Zone
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TRAPPIST-1d is one of seven Earth-sized planets in the TRAPPIST-1 system. About 40 light-years from Earth, TRAPPIST-1 is unusual both for its number of small rocky planets and the number in the habitable zone. Several of the artist's illustrations shown above portray possible water or ice in the system– the proximity of the planets to their red dwarf star may indicate that any of them could have water on their surface. This artist's concept shows TRAPPIST-1d with a narrow band of water near the terminator, the divide between a hot, dry day and an ice-covered night side.

PLANET TYPE
Terrestrial
DISCOVERY DATE
May 2016
MASS
0.41 x Earth
PLANET RADIUS
0.772 x Earth
ORBITAL RADIUS
0.02144 AU
ORBITAL PERIOD
4.05 days
ECCENTRICITY
0.07
DETECTION METHOD
Transit