K2-59 b
K2-59 b is a mini-Neptune orbiting K2-59 in the constellation Aquarius. It lies about 1,015 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-59 b?
K2-59 b has a radius of 2.41 times that of Earth.
Is K2-59 b in the Habitable Zone?
K2-59 b orbits inside the inner edge of the habitable zone of K2-59. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-59: 0.437–1.054 AU (conservative: 0.554–1.000 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 K2-59 b
K2-59 b receives 17.10 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on K2-59 b — one full orbit around K2-59 — lasts 20.7 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.135 AU — closer to its star than Mercury is to the Sun.
How Was K2-59 b Discovered?
K2-59 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 K2-59 b?
K2-59 b is 1,015.4 light-years (311.3 parsecs) from Earth. Light arriving here tonight left the planet around the year 1011. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 17,871,040 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. K2-59 b scores 0.33, ranking #887 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-59
K2-59
- Surface temperature
- 5,055 K (Sun: 5,772 K)
- Mass
- 0.77 M☉
- Radius
- 0.73 R☉
The K2-59 Planetary System
K2-59 b is one of 2 known planets in the K2-59 system. Its siblings:
- K2-59 c (Mini Neptune)
K2-59 b — Complete Data
| Radius | 2.410 Earth radii (0.215 Jupiter radii) |
|---|---|
| Orbital period | 20.69 days |
| Orbital distance | 0.135 AU |
| Stellar irradiation | 17.10× Earth |
| Earth Similarity Index | 0.33 |
| Distance from Earth | 1,015.4 light-years (311.3 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 K2-59 b
Is K2-59 b habitable?
No — K2-59 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-59 b?
K2-59 b is about 1,015 light-years from Earth in the constellation Aquarius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 17,871,040 years to get there.
How big is K2-59 b compared to Earth?
K2-59 b has 2.41 times the radius of Earth.
How long is a year on K2-59 b?
One orbit around K2-59 takes 20.7 Earth days — short enough that 18 of its years would fit into one Earth year.
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