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Planet profiles

KOI-351 c

Lava World · 2,764 light-years away · Last reviewed October 14, 2026

KOI-351 c rendered in TerraForge from its measured mass, orbit and star
TerraForge's rendering of KOI-351 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
Lava World
Host star
KOI-351
Distance
2,764 light-years
Orbit
8.72 days
Mass
1.81 × Earth
Radius
1.19 × Earth
Discovered
2013, transit

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

KOI-351 c, also known as Kepler-90 c, is the second planet of Kepler-90, a Sun-like star about 2,800 light-years away with eight known planets, as many as our solar system. It passes in front of its star every 8.72 days, and the NASA Exoplanet Archive lists it at about 1.2 times Earth's radius, the smallest of the system's original seven.

It was announced in 2013 by a team led by Juan Cabrera, one of four new planets they found in Kepler data. Its orbit is closely linked to that of its inner neighbour, Kepler-90 b: their periods are within half a percent of a 4 to 5 ratio. Pairs like this, near a resonance, pull on each other in a regular rhythm. An independent 2013 analysis by the Planet Hunters citizen-science project, led by Joseph Schmitt, also characterized the system and found its seven candidates dynamically stable.

In 2017 a team led by Christopher Shallue and Andrew Vanderburg used machine learning to find an eighth planet, Kepler-90 i, which orbits just outside Kepler-90 c, every 14.4 days. Kepler-90 c itself is far too hot for liquid water: it receives over 200 times the light Earth gets from the Sun. Its archive mass of about 1.8 Earth masses is an estimate from its size, not a measurement.

Sources

  1. The Planetary System to KIC 11442793: A Compact Analogue to the Solar System — arXiv (The Astrophysical Journal)
  2. Planet Hunters. VI: An Independent Characterization of KOI-351 and Several Long Period Planet Candidates from the Kepler Archival Data — arXiv (The Astronomical Journal)
  3. Identifying Exoplanets with Deep Learning: A Five Planet Resonant Chain around Kepler-80 and an Eighth Planet around Kepler-90 — arXiv (The Astronomical Journal)
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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