K2-31 b
K2-31 b is a hot Jupiter orbiting the G7 V star K2-31 in the constellation Scorpius. It lies about 361 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-31 b?
K2-31 b has a radius of 11.88 times that of Earth, or 1.06 times the radius of Jupiter. Its mass is 564 times that of Earth.
Is K2-31 b in the Habitable Zone?
K2-31 b orbits inside the inner edge of the habitable zone of K2-31. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-31: 0.503–1.203 AU (conservative: 0.637–1.141 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 ›
Orbit and Year Length
A year on K2-31 b — one full orbit around K2-31 — lasts just 30.2 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.022 AU — closer to its star than Mercury is to the Sun.
How Was K2-31 b Discovered?
K2-31 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 K2-31 b?
K2-31 b is 360.5 light-years (110.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1666. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,344,800 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. K2-31 b scores 0.08, ranking #4,786 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-31
K2-31 b belongs to a system of 2 stars; it orbits K2-31.
K2-31
- Spectral type
- G7 V
- Surface temperature
- 5,280 K (Sun: 5,772 K)
- Mass
- 0.91 M☉
- Radius
- 0.78 R☉
Planetary System
K2-31 b is the only planet known to orbit K2-31 so far.
K2-31 b — Complete Data
| Radius | 11.882 Earth radii (1.060 Jupiter radii) |
|---|---|
| Mass | 563.83 Earth masses (1.774 Jupiter masses) |
| Orbital period | 1.26 days |
| Orbital distance | 0.022 AU |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 360.5 light-years (110.5 parsecs) |
| Constellation | Scorpius |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2016-11-30. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-31 b
Is K2-31 b habitable?
No — K2-31 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-31 b?
K2-31 b is about 361 light-years from Earth in the constellation Scorpius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,344,800 years to get there.
How big is K2-31 b compared to Earth?
K2-31 b has 11.88 times the radius of Earth and about 564 times its mass.
How long is a year on K2-31 b?
One orbit around K2-31 takes 1.3 Earth days — short enough that 290 of its years would fit into one Earth year.
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