K2-187 d
K2-187 d is a mini-Neptune orbiting K2-187 in the constellation Cancer. It lies about 1,079 light-years from Earth and was discovered in 2018 using the transit method.
How Big Is K2-187 d?
K2-187 d has a radius of 2.40 times that of Earth.
Is K2-187 d in the Habitable Zone?
The position of K2-187 d relative to the habitable zone of K2-187 cannot be precisely determined from the available orbital data.
Habitable zone of K2-187: 0.563–1.339 AU (conservative: 0.713–1.270 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 K2-187 d — one full orbit around K2-187 — lasts 7.15 Earth days, shorter than Mercury's 88-day year.
How Was K2-187 d Discovered?
K2-187 d was discovered in 2018 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 K2-187 d?
K2-187 d is 1,079.3 light-years (330.9 parsecs) from Earth. Light arriving here tonight left the planet about 1,079 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 18,995,680 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. K2-187 d scores 0.25, ranking #3,191 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-187
K2-187
- Surface temperature
- 5,438 K (Sun: 5,772 K)
- Radius
- 0.83 R☉
The K2-187 Planetary System
K2-187 d is one of 4 known planets in the K2-187 system. Its siblings:
K2-187 d — Complete Data
| Radius | 2.400 Earth radii (0.214 Jupiter radii) |
|---|---|
| Orbital period | 7.15 days |
| Earth Similarity Index | 0.25 |
| Distance from Earth | 1,079.3 light-years (330.9 parsecs) |
| Constellation | Cancer |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2022-03-28. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-187 d
Is K2-187 d habitable?
K2-187 d is not known to orbit within the habitable zone of K2-187, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is K2-187 d?
K2-187 d is about 1,079 light-years from Earth in the constellation Cancer. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 18,995,680 years to get there.
How big is K2-187 d compared to Earth?
K2-187 d has 2.40 times the radius of Earth.
How long is a year on K2-187 d?
One orbit around K2-187 takes 7.1 Earth days — short enough that 51 of its years would fit into one Earth year.
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