Kepler-209 c
Kepler-209 c is a sub-Neptune orbiting Kepler-209 in the constellation Lyra. It lies about 1,882 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-209 c?
Kepler-209 c has a radius of 3.10 times that of Earth.
Is Kepler-209 c in the Habitable Zone?
Kepler-209 c orbits inside the inner edge of the habitable zone of Kepler-209. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-209: 0.649–1.540 AU (conservative: 0.822–1.460 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-209 c — one full orbit around Kepler-209 — lasts 41.7 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.231 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-209 c Discovered?
Kepler-209 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-209 c?
Kepler-209 c is 1,881.7 light-years (576.9 parsecs) from Earth. Light arriving here tonight left the planet about 1,882 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 33,117,920 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-209 c scores 0.29, ranking #1,919 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-209
Kepler-209
- Surface temperature
- 5,513 K (Sun: 5,772 K)
- Radius
- 0.94 R☉
The Kepler-209 Planetary System
Kepler-209 c is one of 2 known planets in the Kepler-209 system. Its siblings:
- Kepler-209 b (Mini Neptune)
Kepler-209 c — Complete Data
| Radius | 3.100 Earth radii (0.277 Jupiter radii) |
|---|---|
| Orbital period | 41.75 days |
| Orbital distance | 0.231 AU |
| Earth Similarity Index | 0.29 |
| Distance from Earth | 1,881.7 light-years (576.9 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-209 c
Is Kepler-209 c habitable?
No — Kepler-209 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-209 c?
Kepler-209 c is about 1,882 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 33,117,920 years to get there.
How big is Kepler-209 c compared to Earth?
Kepler-209 c has 3.10 times the radius of Earth.
How long is a year on Kepler-209 c?
One orbit around Kepler-209 takes 41.7 Earth days.
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