K2-220 b
K2-220 b is a mini-Neptune orbiting K2-220 in the constellation Pisces. It lies about 762 light-years from Earth and was discovered in 2018 using the transit method.
How Big Is K2-220 b?
K2-220 b has a radius of 2.37 times that of Earth.
Is K2-220 b in the Habitable Zone?
The position of K2-220 b relative to the habitable zone of K2-220 cannot be precisely determined from the available orbital data.
Habitable zone of K2-220: 0.734–1.736 AU (conservative: 0.929–1.646 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on K2-220 b
The equilibrium temperature of K2-220 b is about 761 K (488 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C. It receives 79.70 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on K2-220 b — one full orbit around K2-220 — lasts 13.7 Earth days, shorter than Mercury's 88-day year.
How Was K2-220 b Discovered?
K2-220 b was discovered in 2018 using the transit method, with observations from K2.
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is K2-220 b?
K2-220 b is 761.6 light-years (233.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1265. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 13,404,160 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. K2-220 b scores 0.25, ranking #3,020 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-220
K2-220
- Surface temperature
- 5,612 K (Sun: 5,772 K)
- Mass
- 0.91 M☉
- Radius
- 1.03 R☉
Planetary System
K2-220 b is the only planet known to orbit K2-220 so far.
K2-220 b — Complete Data
| Radius | 2.370 Earth radii (0.211 Jupiter radii) |
|---|---|
| Orbital period | 13.68 days |
| Equilibrium temperature | 761 K (488 °C) |
| Stellar irradiation | 79.70× Earth |
| Earth Similarity Index | 0.25 |
| Distance from Earth | 761.6 light-years (233.5 parsecs) |
| Constellation | Pisces |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2025-09-17. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-220 b
Is K2-220 b habitable?
K2-220 b is not known to orbit within the habitable zone of K2-220, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is K2-220 b?
K2-220 b is about 762 light-years from Earth in the constellation Pisces. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 13,404,160 years to get there.
How big is K2-220 b compared to Earth?
K2-220 b has 2.37 times the radius of Earth.
How long is a year on K2-220 b?
One orbit around K2-220 takes 13.7 Earth days — short enough that 27 of its years would fit into one Earth year.
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