K2-85 b
K2-85 b is a super-Earth orbiting K2-85 in the constellation Taurus. It lies about 317 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-85 b?
K2-85 b has a radius of 1.40 times that of Earth. Its mass is 3.2 times that of Earth, giving it a density of 5.90 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is K2-85 b in the Habitable Zone?
The position of K2-85 b relative to the habitable zone of K2-85 cannot be precisely determined from the available orbital data.
Habitable zone of K2-85: 0.307–0.769 AU (conservative: 0.389–0.729 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 K2-85 b
The equilibrium temperature of K2-85 b is about 1,355 K (1,082 °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 800 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on K2-85 b — one full orbit around K2-85 — lasts just 16.4 hours, shorter than Mercury's 88-day year.
How Was K2-85 b Discovered?
K2-85 b was discovered in 2016 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 K2-85 b?
K2-85 b is 317.1 light-years (97.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1709. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 5,580,960 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. K2-85 b scores 0.29, ranking #1,767 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-85
K2-85
- Surface temperature
- 4,232 K (Sun: 5,772 K)
- Mass
- 0.70 M☉
- Radius
- 0.71 R☉
Planetary System
K2-85 b is the only planet known to orbit K2-85 so far.
K2-85 b — Complete Data
| Radius | 1.400 Earth radii (0.125 Jupiter radii) |
|---|---|
| Mass | 3.20 Earth masses (0.010 Jupiter masses) |
| Density | 5.90 g/cm³ (Earth: 5.51) |
| Orbital period | 0.68 days |
| Equilibrium temperature | 1,355 K (1,082 °C) |
| Stellar irradiation | 800.00× Earth |
| Earth Similarity Index | 0.29 |
| Distance from Earth | 317.1 light-years (97.2 parsecs) |
| Constellation | Taurus |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2025-09-17. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-85 b
Is K2-85 b habitable?
K2-85 b is not known to orbit within the habitable zone of K2-85, and as a super-Earth it is an unlikely candidate for life as we know it.
How far away is K2-85 b?
K2-85 b is about 317 light-years from Earth in the constellation Taurus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 5,580,960 years to get there.
How big is K2-85 b compared to Earth?
K2-85 b has 1.40 times the radius of Earth and about 3.2 times its mass.
How long is a year on K2-85 b?
One orbit around K2-85 takes 0.7 Earth days — short enough that 534 of its years would fit into one Earth year.
Explore K2-85 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
