Kepler-321 c
Kepler-321 c is a mini-Neptune orbiting Kepler-321 in the constellation Cygnus. It lies about 1,254 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-321 c?
Kepler-321 c has a radius of 2.32 times that of Earth.
Is Kepler-321 c in the Habitable Zone?
Kepler-321 c orbits inside the inner edge of the habitable zone of Kepler-321. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-321: 0.886–2.090 AU (conservative: 1.123–1.982 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-321 c — one full orbit around Kepler-321 — lasts 13.1 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.110 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-321 c Discovered?
Kepler-321 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-321 c?
Kepler-321 c is 1,254.2 light-years (384.5 parsecs) from Earth. Light arriving here tonight left the planet about 1,254 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 22,073,920 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-321 c scores 0.26, ranking #2,992 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-321
Kepler-321
- Surface temperature
- 5,740 K (Sun: 5,772 K)
- Radius
- 1.19 R☉
The Kepler-321 Planetary System
Kepler-321 c is one of 2 known planets in the Kepler-321 system. Its siblings:
- Kepler-321 b (Super Earth)
Kepler-321 c — Complete Data
| Radius | 2.320 Earth radii (0.207 Jupiter radii) |
|---|---|
| Orbital period | 13.09 days |
| Orbital distance | 0.110 AU |
| Earth Similarity Index | 0.26 |
| Distance from Earth | 1,254.2 light-years (384.5 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-321 c
Is Kepler-321 c habitable?
No — Kepler-321 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-321 c?
Kepler-321 c is about 1,254 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 22,073,920 years to get there.
How big is Kepler-321 c compared to Earth?
Kepler-321 c has 2.32 times the radius of Earth.
How long is a year on Kepler-321 c?
One orbit around Kepler-321 takes 13.1 Earth days — short enough that 28 of its years would fit into one Earth year.
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