Kepler-259 b
Kepler-259 b is a mini-Neptune orbiting Kepler-259 in the constellation Lyra. It lies about 3,269 light-years from Earth and was discovered in 2014 using the transit method.
How Big Is Kepler-259 b?
Kepler-259 b has a radius of 2.80 times that of Earth.
Is Kepler-259 b in the Habitable Zone?
Kepler-259 b orbits inside the inner edge of the habitable zone of Kepler-259. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-259: 0.705–1.654 AU (conservative: 0.893–1.568 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-259 b — one full orbit around Kepler-259 — lasts 8.12 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.079 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-259 b Discovered?
Kepler-259 b 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-259 b?
Kepler-259 b is 3,268.5 light-years (1,002.1 parsecs) from Earth. Light arriving here tonight left the planet about 3,269 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 57,525,600 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-259 b scores 0.23, ranking #3,529 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-259
Kepler-259
- Surface temperature
- 5,938 K (Sun: 5,772 K)
- Radius
- 0.90 R☉
The Kepler-259 Planetary System
Kepler-259 b is one of 2 known planets in the Kepler-259 system. Its siblings:
- Kepler-259 c (Mini Neptune)
Kepler-259 b — Complete Data
| Radius | 2.800 Earth radii (0.250 Jupiter radii) |
|---|---|
| Orbital period | 8.12 days |
| Orbital distance | 0.079 AU |
| Earth Similarity Index | 0.23 |
| Distance from Earth | 3,268.5 light-years (1,002.1 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-259 b
Is Kepler-259 b habitable?
No — Kepler-259 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-259 b?
Kepler-259 b is about 3,269 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 57,525,600 years to get there.
How big is Kepler-259 b compared to Earth?
Kepler-259 b has 2.80 times the radius of Earth.
How long is a year on Kepler-259 b?
One orbit around Kepler-259 takes 8.1 Earth days — short enough that 45 of its years would fit into one Earth year.
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