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Planet profiles

TOI-700 c

Barren · 101 light-years away · Last reviewed October 15, 2026

TOI-700 c rendered in TerraForge from its measured mass, orbit and star
TerraForge's rendering of TOI-700 c, generated by our physics engine from its measured mass, size, orbit and star. An illustration of what the science suggests, not a photograph.
TerraForge classification
Barren
Host star
TOI-700 (M2.5 V)
Distance
101 light-years
Orbit
16.1 days
Mass
6.96 × Earth
Radius
2.54 × Earth
Discovered
2020, transit

Figures from the NASA Exoplanet Archive. The classification is TerraForge’s, from its physics model.

TOI-700 c is the largest planet around TOI-700, a quiet red dwarf about 100 light-years away, and the odd one out in a system of Earth-sized worlds. It is about 2.6 times Earth's width, a sub-Neptune, between Earth and Neptune in size, and orbits every 16.1 days.

It was discovered together with TOI-700 b and d in 2020 by a team led by Emily Gilbert, using NASA's TESS satellite, which caught the dips in starlight as each planet crossed the star. The team ruled out common false alarms with ground-based observations and validated all three. They noted that, while studying the atmosphere of the habitable-zone planet TOI-700 d with the James Webb Space Telescope will be challenging, the larger TOI-700 c will be an excellent target, because a bigger planet blocks more light and leaves a stronger signal of any atmosphere. In 2023 a fourth planet, TOI-700 e, was found orbiting between c and d.

So the system has a sub-Neptune sitting between rocky-sized planets, a pattern that tests how planets of different sizes form and keep their atmospheres around the same star. According to the NASA Exoplanet Archive, TOI-700 c receives about 2.6 times the light Earth gets from the Sun. Its mass has not been measured; the archive's figure of about 7 Earth masses is an estimate from its size. At this size it is likely to have a thick envelope of gas, not a rocky surface.

Sources

  1. The First Habitable Zone Earth-sized Planet from TESS. I: Validation of the TOI-700 System — arXiv (The Astronomical Journal)
  2. A Second Earth-Sized Planet in the Habitable Zone of the M Dwarf, TOI-700 — arXiv (The Astrophysical Journal Letters)
A banded gas giant with four moons in different colors: a yellow sulfur moon, two rust-red rock moons and a blue water moon

New: Choose What Your Moons Are Made Of 🌙

Every moon used to be grey rock, white ice or blue ocean, decided for you. Now each one has a "Made of" choice in the builder's Moons tab — silicate rock, iron, water ice, carbon, sulfur, or nitrogen and methane ice — and the physics decides what that becomes. Put water ice too close to the star and it boils off to bare rock. Put sulfur where a neighbouring moon keeps it tidally flexed and it erupts in Io's yellows. Give a Titan-sized moon nitrogen ice far from the sun and it wraps itself in haze. Hang a water moon about the mass of Earth off a giant planet in the habitable zone and it can hold air and open seas — scored for life on the same scale as a planet, with a day as long as its orbit. A tint slider nudges the colour, but only as far as that material could really go.

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