Kepler-255 c
Kepler-255 c is a mini-Neptune orbiting Kepler-255 in the constellation Cygnus. It lies about 3,433 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-255 c?
Kepler-255 c has a radius of 2.99 times that of Earth.
Is Kepler-255 c in the Habitable Zone?
Kepler-255 c orbits inside the inner edge of the habitable zone of Kepler-255. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-255: 0.582–1.385 AU (conservative: 0.737–1.313 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-255 c — one full orbit around Kepler-255 — lasts 9.95 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.092 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-255 c Discovered?
Kepler-255 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-255 c?
Kepler-255 c is 3,432.9 light-years (1,052.5 parsecs) from Earth. Light arriving here tonight left the planet about 3,433 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 60,419,040 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-255 c scores 0.23, ranking #3,563 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-255
Kepler-255
- Surface temperature
- 5,431 K (Sun: 5,772 K)
- Mass
- 0.90 M☉
- Radius
- 0.86 R☉
- Age
- 4.4 billion years (Sun: 4.6)
The Kepler-255 Planetary System
Kepler-255 c is one of 3 known planets in the Kepler-255 system. Its siblings:
- Kepler-255 b (Super Earth)
- Kepler-255 d (Super Earth)
Kepler-255 c — Complete Data
| Radius | 2.990 Earth radii (0.267 Jupiter radii) |
|---|---|
| Orbital period | 9.95 days |
| Orbital distance | 0.092 AU |
| Earth Similarity Index | 0.23 |
| Distance from Earth | 3,432.9 light-years (1,052.5 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-255 c
Is Kepler-255 c habitable?
No — Kepler-255 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-255 c?
Kepler-255 c is about 3,433 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 60,419,040 years to get there.
How big is Kepler-255 c compared to Earth?
Kepler-255 c has 2.99 times the radius of Earth.
How long is a year on Kepler-255 c?
One orbit around Kepler-255 takes 9.9 Earth days — short enough that 37 of its years would fit into one Earth year.
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