K2-58 b
K2-58 b is a mini-Neptune orbiting K2-58 in the constellation Aquarius. It lies about 593 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-58 b?
K2-58 b has a radius of 2.68 times that of Earth.
Is K2-58 b in the Habitable Zone?
K2-58 b orbits inside the inner edge of the habitable zone of K2-58. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-58: 0.579–1.378 AU (conservative: 0.733–1.307 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 K2-58 b
K2-58 b receives 118 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on K2-58 b — one full orbit around K2-58 — lasts 7.05 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.069 AU — closer to its star than Mercury is to the Sun.
How Was K2-58 b Discovered?
K2-58 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 K2-58 b?
K2-58 b is 592.8 light-years (181.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1434. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 10,433,280 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. K2-58 b scores 0.24, ranking #3,360 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-58
K2-58
- Surface temperature
- 5,413 K (Sun: 5,772 K)
- Mass
- 0.89 M☉
- Radius
- 0.86 R☉
The K2-58 Planetary System
K2-58 b is one of 3 known planets in the K2-58 system. Its siblings:
K2-58 b — Complete Data
| Radius | 2.680 Earth radii (0.239 Jupiter radii) |
|---|---|
| Orbital period | 7.05 days |
| Orbital distance | 0.069 AU |
| Stellar irradiation | 118.00× Earth |
| Earth Similarity Index | 0.24 |
| Distance from Earth | 592.8 light-years (181.7 parsecs) |
| Constellation | Aquarius |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2016-07-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-58 b
Is K2-58 b habitable?
No — K2-58 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-58 b?
K2-58 b is about 593 light-years from Earth in the constellation Aquarius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 10,433,280 years to get there.
How big is K2-58 b compared to Earth?
K2-58 b has 2.68 times the radius of Earth.
How long is a year on K2-58 b?
One orbit around K2-58 takes 7.1 Earth days — short enough that 52 of its years would fit into one Earth year.
Explore K2-58 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.
