Kepler-69 b
Kepler-69 b is a mini-Neptune orbiting the G4 V star Kepler-69 in the constellation Cygnus. It lies about 2,383 light-years from Earth and was discovered in 2013 using the transit method.
How Big Is Kepler-69 b?
Kepler-69 b has a radius of 2.24 times that of Earth.
Is Kepler-69 b in the Habitable Zone?
Kepler-69 b orbits inside the inner edge of the habitable zone of Kepler-69. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-69: 0.677–1.601 AU (conservative: 0.857–1.518 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Kepler-69 b
The equilibrium temperature of Kepler-69 b is about 779 K (506 °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.
Orbit and Year Length
A year on Kepler-69 b — one full orbit around Kepler-69 — lasts 13.7 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.094 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.16).
How Was Kepler-69 b Discovered?
Kepler-69 b 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-69 b?
Kepler-69 b is 2,383.0 light-years (730.6 parsecs) from Earth. Light arriving here tonight left the planet about 2,383 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 41,940,800 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-69 b scores 0.26, ranking #2,943 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-69
Kepler-69
- Spectral type
- G4 V
- Surface temperature
- 5,638 K (Sun: 5,772 K)
- Mass
- 0.81 M☉
- Radius
- 0.93 R☉
- Luminosity
- 0.7998 L☉
The Kepler-69 Planetary System
Kepler-69 b is one of 2 known planets in the Kepler-69 system. Its siblings:
- Kepler-69 c (Super Earth)
Kepler-69 b — Complete Data
| Radius | 2.240 Earth radii (0.200 Jupiter radii) |
|---|---|
| Orbital period | 13.72 days |
| Orbital distance | 0.094 AU |
| Eccentricity | 0.160 |
| Equilibrium temperature | 779 K (506 °C) |
| Earth Similarity Index | 0.26 |
| Distance from Earth | 2,383.0 light-years (730.6 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2013 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-69 b
Is Kepler-69 b habitable?
No — Kepler-69 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-69 b?
Kepler-69 b is about 2,383 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 41,940,800 years to get there.
How big is Kepler-69 b compared to Earth?
Kepler-69 b has 2.24 times the radius of Earth.
How long is a year on Kepler-69 b?
One orbit around Kepler-69 takes 13.7 Earth days — short enough that 27 of its years would fit into one Earth year.
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