Kepler-15 b
Kepler-15 b is a hot Jupiter orbiting Kepler-15 in the constellation Cygnus. It lies about 2,412 light-years from Earth and was discovered in 2011 using the transit method.
How Big Is Kepler-15 b?
Kepler-15 b has a radius of 10.76 times that of Earth, or 0.96 times the radius of Jupiter. Its mass is 210 times that of Earth, giving it a density of 0.93 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is Kepler-15 b in the Habitable Zone?
Kepler-15 b orbits inside the inner edge of the habitable zone of Kepler-15. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-15: 0.690–1.637 AU (conservative: 0.873–1.552 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-15 b — one full orbit around Kepler-15 — lasts 4.94 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.057 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.06).
How Was Kepler-15 b Discovered?
Kepler-15 b was discovered in 2011 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-15 b?
Kepler-15 b is 2,411.6 light-years (739.4 parsecs) from Earth. Light arriving here tonight left the planet about 2,412 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 42,444,160 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-15 b scores 0.09, ranking #4,565 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-15
Kepler-15
- Surface temperature
- 5,515 K (Sun: 5,772 K)
- Mass
- 1.02 M☉
- Radius
- 0.99 R☉
- Luminosity
- 0.8185 L☉
- Age
- 3.7 billion years (Sun: 4.6)
Planetary System
Kepler-15 b is the only planet known to orbit Kepler-15 so far.
Kepler-15 b — Complete Data
| Radius | 10.760 Earth radii (0.960 Jupiter radii) |
|---|---|
| Mass | 209.76 Earth masses (0.660 Jupiter masses) |
| Density | 0.93 g/cm³ (Earth: 5.51) |
| Orbital period | 4.94 days |
| Orbital distance | 0.057 AU |
| Eccentricity | 0.060 |
| Earth Similarity Index | 0.09 |
| Distance from Earth | 2,411.6 light-years (739.4 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2011 |
Data: NASA Exoplanet Archive, last updated 2014-05-14. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-15 b
Is Kepler-15 b habitable?
No — Kepler-15 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-15 b?
Kepler-15 b is about 2,412 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 42,444,160 years to get there.
How big is Kepler-15 b compared to Earth?
Kepler-15 b has 10.76 times the radius of Earth and about 210 times its mass.
How long is a year on Kepler-15 b?
One orbit around Kepler-15 takes 4.9 Earth days — short enough that 74 of its years would fit into one Earth year.
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