Kepler-37 c
Kepler-37 c is a terrestrial planet orbiting Kepler-37 in the constellation Lyra. It lies about 209 light-years from Earth and was discovered in 2013 using the transit method.
How Big Is Kepler-37 c?
Kepler-37 c has a radius of 0.76 times that of Earth. Its mass is 1.3 times that of Earth, giving it a density of 15.00 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is Kepler-37 c in the Habitable Zone?
Kepler-37 c orbits inside the inner edge of the habitable zone of Kepler-37. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-37: 0.522–1.244 AU (conservative: 0.661–1.180 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-37 c
The equilibrium temperature of Kepler-37 c is about 615 K (342 °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. It receives 23.90 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Kepler-37 c — one full orbit around Kepler-37 — lasts 21.3 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.139 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.10).
How Was Kepler-37 c Discovered?
Kepler-37 c was discovered in 2013 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-37 c?
Kepler-37 c is 208.5 light-years (63.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1818. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,669,600 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-37 c scores 0.34, ranking #846 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-37
Kepler-37
- Surface temperature
- 5,357 K (Sun: 5,772 K)
- Mass
- 0.79 M☉
- Radius
- 0.79 R☉
- Age
- 7.6 billion years (Sun: 4.6)
The Kepler-37 Planetary System
Kepler-37 c is one of 4 known planets in the Kepler-37 system. Its siblings:
- Kepler-37 b (Terrestrial)
- Kepler-37 d (Puffy Planet)
- Kepler-37 e
Kepler-37 c — Complete Data
| Radius | 0.755 Earth radii (0.067 Jupiter radii) |
|---|---|
| Mass | 1.30 Earth masses (0.004 Jupiter masses) |
| Density | 15.00 g/cm³ (Earth: 5.51) |
| Orbital period | 21.30 days |
| Orbital distance | 0.139 AU |
| Eccentricity | 0.099 |
| Equilibrium temperature | 615 K (342 °C) |
| Stellar irradiation | 23.90× Earth |
| Earth Similarity Index | 0.34 |
| Distance from Earth | 208.5 light-years (63.9 parsecs) |
| Constellation | Lyra |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2013 |
Data: NASA Exoplanet Archive, last updated 2023-04-17. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-37 c
Is Kepler-37 c habitable?
No — Kepler-37 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-37 c?
Kepler-37 c is about 209 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,669,600 years to get there.
How big is Kepler-37 c compared to Earth?
Kepler-37 c has 0.76 times the radius of Earth and about 1.3 times its mass.
How long is a year on Kepler-37 c?
One orbit around Kepler-37 takes 21.3 Earth days — short enough that 17 of its years would fit into one Earth year.
Explore Kepler-37 c in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
