K2-318 b
K2-318 b is a super-Earth orbiting K2-318 in the constellation Libra. It lies about 482 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is K2-318 b?
K2-318 b has a radius of 1.66 times that of Earth.
Is K2-318 b in the Habitable Zone?
K2-318 b orbits inside the inner edge of the habitable zone of K2-318. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-318: 0.199–0.509 AU (conservative: 0.253–0.482 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 K2-318 b
The equilibrium temperature of K2-318 b is about 456 K (183 °C) — hotter than anywhere on Earth. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C.
Orbit and Year Length
A year on K2-318 b — one full orbit around K2-318 — lasts 7.01 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.091 AU — closer to its star than Mercury is to the Sun.
How Was K2-318 b Discovered?
K2-318 b was discovered in 2020 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 K2-318 b?
K2-318 b is 482.3 light-years (147.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1544. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 8,488,480 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. K2-318 b scores 0.46, ranking #324 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-318
K2-318
- Surface temperature
- 3,851 K (Sun: 5,772 K)
- Mass
- 0.56 M☉
- Radius
- 0.55 R☉
Planetary System
K2-318 b is the only planet known to orbit K2-318 so far.
K2-318 b — Complete Data
| Radius | 1.660 Earth radii (0.148 Jupiter radii) |
|---|---|
| Orbital period | 7.01 days |
| Orbital distance | 0.091 AU |
| Equilibrium temperature | 456 K (183 °C) |
| Earth Similarity Index | 0.46 |
| Distance from Earth | 482.3 light-years (147.9 parsecs) |
| Constellation | Libra |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2020-09-09. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-318 b
Is K2-318 b habitable?
No — K2-318 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-318 b?
K2-318 b is about 482 light-years from Earth in the constellation Libra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 8,488,480 years to get there.
How big is K2-318 b compared to Earth?
K2-318 b has 1.66 times the radius of Earth.
How long is a year on K2-318 b?
One orbit around K2-318 takes 7.0 Earth days — short enough that 52 of its years would fit into one Earth year.
Explore K2-318 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.
