K2-381 d
K2-381 d is a super-Earth orbiting K2-381 in the constellation Sagittarius. It lies about 475 light-years from Earth and was discovered in 2022 using the transit method.
How Big Is K2-381 d?
K2-381 d has a radius of 1.69 times that of Earth.
Is K2-381 d in the Habitable Zone?
The position of K2-381 d relative to the habitable zone of K2-381 cannot be precisely determined from the available orbital data.
Habitable zone of K2-381: 0.324–0.801 AU (conservative: 0.410–0.759 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 K2-381 d — one full orbit around K2-381 — lasts 26.8 Earth days, shorter than Mercury's 88-day year.
How Was K2-381 d Discovered?
K2-381 d 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 K2-381 d?
K2-381 d is 475.2 light-years (145.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1551. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 8,363,520 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. K2-381 d scores 0.44, ranking #373 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-381
K2-381
- Surface temperature
- 4,473 K (Sun: 5,772 K)
- Mass
- 0.75 M☉
- Radius
- 0.68 R☉
The K2-381 Planetary System
K2-381 d is one of 3 known planets in the K2-381 system. Its siblings:
K2-381 d — Complete Data
| Radius | 1.689 Earth radii (0.151 Jupiter radii) |
|---|---|
| Orbital period | 26.80 days |
| Earth Similarity Index | 0.44 |
| Distance from Earth | 475.2 light-years (145.7 parsecs) |
| Constellation | Sagittarius |
| 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 K2-381 d
Is K2-381 d habitable?
K2-381 d is not known to orbit within the habitable zone of K2-381, and as a super-Earth it is an unlikely candidate for life as we know it.
How far away is K2-381 d?
K2-381 d is about 475 light-years from Earth in the constellation Sagittarius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 8,363,520 years to get there.
How big is K2-381 d compared to Earth?
K2-381 d has 1.69 times the radius of Earth.
How long is a year on K2-381 d?
One orbit around K2-381 takes 26.8 Earth days — short enough that 14 of its years would fit into one Earth year.
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