Kepler-431 d
Kepler-431 d is a terrestrial planet orbiting Kepler-431 in the constellation Lyra. It lies about 1,587 light-years from Earth and was discovered in 2015 using the transit method.
How Big Is Kepler-431 d?
Kepler-431 d has a radius of 1.11 times that of Earth.
Is Kepler-431 d in the Habitable Zone?
Kepler-431 d orbits inside the inner edge of the habitable zone of Kepler-431. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-431: 0.873–2.045 AU (conservative: 1.106–1.939 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 Kepler-431 d
The equilibrium temperature of Kepler-431 d is about 856 K (583 °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 Kepler-431 d — one full orbit around Kepler-431 — lasts 11.9 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.105 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-431 d Discovered?
Kepler-431 d was discovered in 2015 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-431 d?
Kepler-431 d is 1,586.9 light-years (486.5 parsecs) from Earth. Light arriving here tonight left the planet about 1,587 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 27,929,440 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-431 d scores 0.30, ranking #1,477 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-431
Kepler-431
- Surface temperature
- 6,004 K (Sun: 5,772 K)
- Mass
- 1.07 M☉
- Radius
- 1.09 R☉
The Kepler-431 Planetary System
Kepler-431 d is one of 3 known planets in the Kepler-431 system. Its siblings:
- Kepler-431 b (Terrestrial)
- Kepler-431 c (Terrestrial)
Kepler-431 d — Complete Data
| Radius | 1.110 Earth radii (0.100 Jupiter radii) |
|---|---|
| Orbital period | 11.92 days |
| Orbital distance | 0.105 AU |
| Equilibrium temperature | 856 K (583 °C) |
| Earth Similarity Index | 0.30 |
| Distance from Earth | 1,586.9 light-years (486.5 parsecs) |
| Constellation | Lyra |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2015 |
Data: NASA Exoplanet Archive, last updated 2014-11-19. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-431 d
Is Kepler-431 d habitable?
No — Kepler-431 d orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-431 d?
Kepler-431 d is about 1,587 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 27,929,440 years to get there.
How big is Kepler-431 d compared to Earth?
Kepler-431 d has 1.11 times the radius of Earth.
How long is a year on Kepler-431 d?
One orbit around Kepler-431 takes 11.9 Earth days — short enough that 31 of its years would fit into one Earth year.
Explore Kepler-431 d in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
