Kepler-10 b
Kepler-10 b is a lava world orbiting Kepler-10 in the constellation Draco. It lies about 605 light-years from Earth and was discovered in 2011 using the transit method.
How Big Is Kepler-10 b?
Kepler-10 b has a radius of 1.47 times that of Earth. Its mass is 3.2 times that of Earth, giving it a density of 5.54 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is Kepler-10 b in the Habitable Zone?
Kepler-10 b orbits inside the inner edge of the habitable zone of Kepler-10. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-10: 0.783–1.849 AU (conservative: 0.992–1.753 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Kepler-10 b
The equilibrium temperature of Kepler-10 b is about 2,188 K (1,915 °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-10 b — one full orbit around Kepler-10 — lasts just 20.1 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.017 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-10 b Discovered?
Kepler-10 b was discovered in 2011 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-10 b?
Kepler-10 b is 605.0 light-years (185.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1421. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 10,648,000 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-10 b scores 0.28, ranking #2,232 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-10
Kepler-10
- Surface temperature
- 5,708 K (Sun: 5,772 K)
- Mass
- 0.91 M☉
- Radius
- 1.07 R☉
- Age
- 10.6 billion years (Sun: 4.6)
The Kepler-10 Planetary System
Kepler-10 b is one of 3 known planets in the Kepler-10 system. Its siblings:
- Kepler-10 c (Super Earth)
- Kepler-10 d (Neptune-like)
Kepler-10 b — Complete Data
| Radius | 1.470 Earth radii (0.131 Jupiter radii) |
|---|---|
| Mass | 3.24 Earth masses (0.010 Jupiter masses) |
| Density | 5.54 g/cm³ (Earth: 5.51) |
| Orbital period | 0.84 days |
| Orbital distance | 0.017 AU |
| Equilibrium temperature | 2,188 K (1,915 °C) |
| Earth Similarity Index | 0.28 |
| Distance from Earth | 605.0 light-years (185.5 parsecs) |
| Constellation | Draco |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2011 |
Data: NASA Exoplanet Archive, last updated 2025-06-11. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-10 b
Is Kepler-10 b habitable?
No — Kepler-10 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-10 b?
Kepler-10 b is about 605 light-years from Earth in the constellation Draco. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 10,648,000 years to get there.
How big is Kepler-10 b compared to Earth?
Kepler-10 b has 1.47 times the radius of Earth and about 3.2 times its mass.
How long is a year on Kepler-10 b?
One orbit around Kepler-10 takes 0.8 Earth days — short enough that 436 of its years would fit into one Earth year.
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