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Planet profiles

K2-72 c

Rocky Terrestrial · 216 light-years away · Last reviewed October 14, 2026

K2-72 c rendered in TerraForge from its measured mass, orbit and star
TerraForge's rendering of K2-72 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
Rocky Terrestrial
Host star
K2-72
Distance
216 light-years
Orbit
15.2 days
Mass
1.65 × Earth
Radius
1.16 × Earth
Discovered
2016, transit

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

K2-72 c is the third of four planets around K2-72, a red dwarf about 220 light-years away. It crosses in front of its star every 15.2 days, and the NASA Exoplanet Archive lists its radius as about 1.16 times Earth's. It was found by NASA's K2 mission, the second phase of the Kepler space telescope, which spotted the small dips in starlight as each of the four planets passed in front of the star.

A team led by Ian Crossfield validated the four planets in 2016, from K2's first year of data, and highlighted the system for its compact layout, with orbits near simple ratios of one another. Measuring the star more precisely changes every planet's size, because a transit reveals a planet's size only in proportion to its star's. That was done in 2017 by a team led by Courtney Dressing, using infrared spectra of the star.

K2-72 c receives about 2.2 times the light Earth gets from the Sun, according to the archive, and has an estimated equilibrium temperature of about 330 kelvin. That puts it warmer than its outer sibling K2-72 e, which Dressing's team placed inside the star's optimistic habitable zone. Its mass of about 1.65 Earth masses in the archive is an estimate based on its size, not a measurement, so its makeup is not known.

Sources

  1. 197 Candidates and 104 Validated Planets in K2's First Five Fields — arXiv (The Astrophysical Journal Supplement Series)
  2. Characterizing K2 Candidate Planetary Systems Orbiting Low-Mass Stars II: Planetary Systems Observed During Campaigns 1-7 — arXiv (The Astronomical Journal)
  3. K2-72 Overview — NASA Exoplanet Archive
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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