Kepler-388 c
Kepler-388 c is a terrestrial planet orbiting Kepler-388 in the constellation Lyra. It lies about 1,386 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-388 c?
Kepler-388 c has a radius of 0.86 times that of Earth.
Is Kepler-388 c in the Habitable Zone?
Kepler-388 c orbits inside the inner edge of the habitable zone of Kepler-388. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-388: 0.284–0.702 AU (conservative: 0.360–0.665 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-388 c — one full orbit around Kepler-388 — lasts 13.3 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.093 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-388 c Discovered?
Kepler-388 c 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-388 c?
Kepler-388 c is 1,386.2 light-years (425.0 parsecs) from Earth. Light arriving here tonight left the planet about 1,386 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 24,397,120 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-388 c scores 0.32, ranking #985 of 5,565 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-388
Kepler-388
- Surface temperature
- 4,498 K (Sun: 5,772 K)
- Radius
- 0.59 R☉
The Kepler-388 Planetary System
Kepler-388 c is one of 2 known planets in the Kepler-388 system. Its siblings:
- Kepler-388 b (Terrestrial)
Kepler-388 c — Complete Data
| Radius | 0.860 Earth radii (0.077 Jupiter radii) |
|---|---|
| Orbital period | 13.30 days |
| Orbital distance | 0.093 AU |
| Earth Similarity Index | 0.32 |
| Distance from Earth | 1,386.2 light-years (425.0 parsecs) |
| Constellation | Lyra |
| 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-388 c
Is Kepler-388 c habitable?
No — Kepler-388 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-388 c?
Kepler-388 c is about 1,386 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 24,397,120 years to get there.
How big is Kepler-388 c compared to Earth?
Kepler-388 c has 0.86 times the radius of Earth.
How long is a year on Kepler-388 c?
One orbit around Kepler-388 takes 13.3 Earth days — short enough that 27 of its years would fit into one Earth year.
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