K2-351 b
K2-351 b is a mini-Neptune orbiting K2-351 in the constellation Virgo. It lies about 2,266 light-years from Earth and was discovered in 2021 using the transit method.
How Big Is K2-351 b?
K2-351 b has a radius of 2.54 times that of Earth.
Is K2-351 b in the Habitable Zone?
The position of K2-351 b relative to the habitable zone of K2-351 cannot be precisely determined from the available orbital data.
Habitable zone of K2-351: 0.786–1.852 AU (conservative: 0.996–1.756 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 K2-351 b
The equilibrium temperature of K2-351 b is about 934 K (661 °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.
Orbit and Year Length
A year on K2-351 b — one full orbit around K2-351 — lasts 7.81 Earth days, shorter than Mercury's 88-day year.
How Was K2-351 b Discovered?
K2-351 b was discovered in 2021 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 K2-351 b?
K2-351 b is 2,265.9 light-years (694.7 parsecs) from Earth. Light arriving here tonight left the planet about 2,266 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 39,879,840 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. K2-351 b scores 0.24, ranking #3,396 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-351
K2-351
- Surface temperature
- 5,769 K (Sun: 5,772 K)
- Mass
- 1.02 M☉
- Radius
- 1.05 R☉
Planetary System
K2-351 b is the only planet known to orbit K2-351 so far.
K2-351 b — Complete Data
| Radius | 2.540 Earth radii (0.227 Jupiter radii) |
|---|---|
| Orbital period | 7.81 days |
| Equilibrium temperature | 934 K (661 °C) |
| Earth Similarity Index | 0.24 |
| Distance from Earth | 2,265.9 light-years (694.7 parsecs) |
| Constellation | Virgo |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2021-08-23. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-351 b
Is K2-351 b habitable?
K2-351 b is not known to orbit within the habitable zone of K2-351, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is K2-351 b?
K2-351 b is about 2,266 light-years from Earth in the constellation Virgo. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 39,879,840 years to get there.
How big is K2-351 b compared to Earth?
K2-351 b has 2.54 times the radius of Earth.
How long is a year on K2-351 b?
One orbit around K2-351 takes 7.8 Earth days — short enough that 47 of its years would fit into one Earth year.
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