K2-405 b
K2-405 b is a Neptune-like planet orbiting K2-405 in the constellation Leo. It lies about 643 light-years from Earth and was discovered in 2022 using the transit method.
How Big Is K2-405 b?
K2-405 b has a radius of 4.57 times that of Earth.
Is K2-405 b in the Habitable Zone?
The position of K2-405 b relative to the habitable zone of K2-405 cannot be precisely determined from the available orbital data.
Habitable zone of K2-405: 0.437–1.060 AU (conservative: 0.554–1.005 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 K2-405 b — one full orbit around K2-405 — lasts 3.44 Earth days, shorter than Mercury's 88-day year.
How Was K2-405 b Discovered?
K2-405 b was discovered in 2022 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 K2-405 b?
K2-405 b is 643.3 light-years (197.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1383. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 11,322,080 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. K2-405 b scores 0.17, ranking #4,104 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-405
K2-405
- Surface temperature
- 4,927 K (Sun: 5,772 K)
- Mass
- 1.03 M☉
- Radius
- 0.77 R☉
Planetary System
K2-405 b is the only planet known to orbit K2-405 so far.
K2-405 b — Complete Data
| Radius | 4.569 Earth radii (0.408 Jupiter radii) |
|---|---|
| Orbital period | 3.44 days |
| Earth Similarity Index | 0.17 |
| Distance from Earth | 643.3 light-years (197.2 parsecs) |
| Constellation | Leo |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-03-16. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-405 b
Is K2-405 b habitable?
K2-405 b is not known to orbit within the habitable zone of K2-405, and as a Neptune-like planet it is an unlikely candidate for life as we know it.
How far away is K2-405 b?
K2-405 b is about 643 light-years from Earth in the constellation Leo. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 11,322,080 years to get there.
How big is K2-405 b compared to Earth?
K2-405 b has 4.57 times the radius of Earth.
How long is a year on K2-405 b?
One orbit around K2-405 takes 3.4 Earth days — short enough that 106 of its years would fit into one Earth year.
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