Kepler-250 d
Kepler-250 d is a mini-Neptune orbiting Kepler-250 in the constellation Cygnus. It lies about 2,481 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-250 d?
Kepler-250 d has a radius of 2.18 times that of Earth.
Is Kepler-250 d in the Habitable Zone?
Kepler-250 d orbits inside the inner edge of the habitable zone of Kepler-250. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-250: 0.499–1.199 AU (conservative: 0.632–1.137 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 Kepler-250 d — one full orbit around Kepler-250 — lasts 17.6 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.127 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-250 d Discovered?
Kepler-250 d was discovered in 2014 using the transit method, with observations from Kepler.
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 Kepler-250 d?
Kepler-250 d is 2,480.7 light-years (760.6 parsecs) from Earth. Light arriving here tonight left the planet about 2,481 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 43,660,320 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. Kepler-250 d scores 0.30, ranking #1,264 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-250
Kepler-250
- Surface temperature
- 5,160 K (Sun: 5,772 K)
- Radius
- 0.81 R☉
The Kepler-250 Planetary System
Kepler-250 d is one of 3 known planets in the Kepler-250 system. Its siblings:
- Kepler-250 b (Terrestrial)
- Kepler-250 c (Mini Neptune)
Kepler-250 d — Complete Data
| Radius | 2.180 Earth radii (0.194 Jupiter radii) |
|---|---|
| Orbital period | 17.65 days |
| Orbital distance | 0.127 AU |
| Earth Similarity Index | 0.30 |
| Distance from Earth | 2,480.7 light-years (760.6 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2014 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-250 d
Is Kepler-250 d habitable?
No — Kepler-250 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-250 d?
Kepler-250 d is about 2,481 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 43,660,320 years to get there.
How big is Kepler-250 d compared to Earth?
Kepler-250 d has 2.18 times the radius of Earth.
How long is a year on Kepler-250 d?
One orbit around Kepler-250 takes 17.6 Earth days — short enough that 21 of its years would fit into one Earth year.
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