Host star — K2-72
- Spectral type
- —
- Temperature
- 3,360 K
- Radius
- 0.33 R☉
- Mass
- 0.27 M☉
- Luminosity
- 0.015 L☉
- Distance
- 66.4 pc (217 ly)
Very cool — a faint red dwarf.
K2-72 e
Orbits K2-72 · 217 light-years from Earth
RockyTransit2016ESI 81 · Very Earth-like
Radius
1.29×
Earth
Mass
2.2×
Earth
Year
24d
Temp
286 K
13°C
Gravity
1.3×
Earth
Distance
217
ly
Could life exist here?
AI analysisK2-72 e is a rocky world roughly 1.3 times Earth's radius with a mass of 2.21 Earth masses, orbiting a cool, dim red dwarf star 217 light-years away. Its equilibrium temperature of 286 Kelvin—just above the freezing point of water—places it squarely in the habitable zone, making it one of the more promising candidates for potentially hosting liquid water on its surface. The planet completes an orbit every 24.2 days at a distance of 0.106 AU, similar to Venus's proximity to our Sun but receiving far less energy because its host star is so much cooler and dimmer than ours. With a density of 5.66 grams per cubic centimeter, slightly denser than Earth, the planet likely has a substantial iron core and rocky composition. The main unknowns are whether K2-72 e has retained an atmosphere, what its surface conditions actually are, and whether the modest eccentricity of 0.11 causes significant climate swings. Discovered in 2016 via the transit method and boasting a habitability score of 81, this world deserves closer study to constrain its atmospheric composition and surface environment.
What it would be like
K2-72 e is a rocky world, potentially similar in composition to Earth or Mars — a solid surface you could, in theory, stand on.
Surface gravity is about 1.3g — noticeably heavier what you're used to on Earth.
With an equilibrium temperature around 13°C, this planet sits in the temperature range where liquid water could potentially exist on the surface — a key ingredient for life as we know it.
An orbital period of 24 days makes the year 15.1× shorter than Earth's. You'd celebrate your birthday more often here.
Earth comparison
Logarithmic bars so Jupiter-class planets fit the same scale as Earth-size worlds.
Radius1.29R⊕
1/25×Earth = 125×
Mass2.21M⊕
1/10000×Earth = 110000×
Surface gravity1.33g
1/100×Earth = 1100×
Equilibrium temp286 K(13°C)
0 KEarth 255 K2500 K
Side-by-side with Earth
Temperature in context
Liquid N₂Mars avgEarth eq.Earth sfc.Boiling H₂OVenus
Discovery & orbit
- Method
- Transit
- Year
- 2016
- Facility
- K2
- Semi-major axis
- 0.1060 AU
- Period
- 24.16 days
- Eccentricity
- 0.1100
- Density
- 5.66 g/cm³
Detected by measuring the tiny dip in starlight as the planet crosses in front of its star.
Noticeably elliptical. Seasons (if any) would vary in intensity.
Rocky composition likely. Earth is 5.51 g/cm³.
Discovered via · Transit
Tiny dip in starlight as the planet crosses in front of its star
A transit photometer watches a star nonstop and measures its brightness to ~0.01%. When a planet passes between us and the star, the star dims briefly — the deeper the dip, the bigger the planet. This is how Kepler and TESS found most known exoplanets.
- Overall share
- ~75% of all confirmed worlds
- Best for
- Earth-to-Neptune-sized planets on short orbits
Orbital Animation
K2-72K2-72 eOrbitHabitable zone
Drag to rotate · scroll to zoomSemi-major axis: 0.106 AUEccentricity: 0.1100Period: 24.2 days
Hertzsprung–Russell Diagram
Where this host star sits among … exoplanet host stars. The main sequence band runs diagonally — giants and supergiants sit above, white dwarfs below.
OBAFGKMCurrent star
How far is 217 light-years?
- A light beam leaving Earth right now would arrive in 217 years.
- At Voyager 1's speed (17 km/s), the trip would take approximately 3.8 million years.
- A radio signal sent today would arrive in 216.7 years — and the reply wouldn't come back for twice that.
Earth Similarity Index
81/1000 — Nothing like Earth100 — Identical to Earth
ESI combines radius similarity and equilibrium temperature similarity. Earth = 100. Mars ≈ 73. Venus ≈ 44. This score reflects two physical parameters only — not atmosphere, water, or magnetic field.