Seven rocky worlds, forty light-years away

TRAPPIST-1

Seven Earth-sized planets in a compact, resonant chain around a tiny ultracool dwarf. Hover for a quick look, or select a planet to read its full field notes.

TRAPPIST-1 An ultracool dwarf at the small, dim end of the stellar family, hosting seven rocky planets. Type M8V ultracool dwarf Distance 40.7 light-years Mass About 0.09 Suns Temperature About 2,566 K TRAPPIST-1 b Confirmed The innermost world: a scorched, roughly Earth-sized rock close to its star. Solar Distance 0.0115 AU · 1.73 million km Size and Gravity 1.12 Earth radii · 1.37 Earth masses Atmosphere and Weather No detectable atmosphere; likely bare rock Moons and Satellites None known Day and Year 1.51-day orbit; likely tidally locked Surface Temperature Estimated around 400 K Habitability Verdict Too hot for surface liquid water TRAPPIST-1 c Confirmed A hot, Earth-sized rock with a thin or absent atmosphere. Solar Distance 0.0158 AU · 2.36 million km Size and Gravity 1.10 Earth radii · 1.31 Earth masses Atmosphere and Weather No thick atmosphere detected Moons and Satellites None known Day and Year 2.42-day orbit; likely tidally locked Surface Temperature Estimated around 342 K Habitability Verdict Too hot for surface liquid water TRAPPIST-1 d Confirmed The smallest of the family, near the inner edge of the temperate zone. Solar Distance 0.0223 AU · 3.34 million km Size and Gravity 0.79 Earth radii · 0.39 Earth masses Atmosphere and Weather Unknown; a thin atmosphere may have been stripped Moons and Satellites None known Day and Year 4.05-day orbit; likely tidally locked Surface Temperature Estimated around 288 K Habitability Verdict Possible inner-edge temperate world; hot by Earth standards TRAPPIST-1 e Confirmed A temperate, Earth-sized world in the middle of the habitable zone. Solar Distance 0.0292 AU · 4.37 million km Size and Gravity 0.92 Earth radii · 0.69 Earth masses Atmosphere and Weather Unknown; no atmosphere directly detected Moons and Satellites None known Day and Year 6.10-day orbit; likely tidally locked Surface Temperature Estimated around 250 K Habitability Verdict Inside the habitable zone; surface conditions unknown TRAPPIST-1 f Confirmed A cool, Earth-sized world toward the outer side of the habitable zone. Solar Distance 0.0385 AU · 5.76 million km Size and Gravity 1.05 Earth radii · 1.04 Earth masses Atmosphere and Weather Unknown; no atmosphere directly detected Moons and Satellites None known Day and Year 9.21-day orbit; likely tidally locked Surface Temperature Estimated around 219 K Habitability Verdict Inside the habitable zone; surface conditions unknown TRAPPIST-1 g Confirmed The largest member of the chain, at the cool outer edge of the temperate zone. Solar Distance 0.0468 AU · 7.00 million km Size and Gravity 1.13 Earth radii · 1.32 Earth masses Atmosphere and Weather Unknown; no atmosphere directly detected Moons and Satellites None known Day and Year 12.35-day orbit; likely tidally locked Surface Temperature Estimated around 199 K Habitability Verdict Outer habitable zone; would need a strong greenhouse to stay warm TRAPPIST-1 h Confirmed The outermost world: a small, frozen body in a slow 18.8-day orbit. Solar Distance 0.0619 AU · 9.26 million km Size and Gravity 0.76 Earth radii · 0.33 Earth masses Atmosphere and Weather Unknown; no atmosphere detected Moons and Satellites None known Day and Year 18.77-day orbit; rotation unknown Surface Temperature Estimated around 173 K Habitability Verdict Too cold for surface liquid water

A tiny ultracool star · seven Earth-sized, likely rocky planets

Orbit spacing and animation are illustrative, not to scale. Orbital periods are shown in the planet notes.

Planet data: NASA Exoplanet Archive · NASA TRAPPIST-1 catalog · Gillon et al. 2017