Kepler-5 b
Kepler-5 b is a hot Jupiter orbiting Kepler-5 in the constellation Cygnus. It lies about 2,935 light-years from Earth and was discovered in 2009 using the transit method.
How Big Is Kepler-5 b?
Kepler-5 b has a radius of 15.98 times that of Earth, or 1.43 times the radius of Jupiter. Its mass is 671 times that of Earth, giving it a density of 0.40 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is Kepler-5 b in the Habitable Zone?
Kepler-5 b orbits inside the inner edge of the habitable zone of Kepler-5. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-5: 1.549–3.607 AU (conservative: 1.961–3.419 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Kepler-5 b
The equilibrium temperature of Kepler-5 b is about 1,750 K (1,477 °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-5 b — one full orbit around Kepler-5 — lasts 3.55 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.054 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-5 b Discovered?
Kepler-5 b was discovered in 2009 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-5 b?
Kepler-5 b is 2,934.7 light-years (899.8 parsecs) from Earth. Light arriving here tonight left the planet about 2,935 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 51,650,720 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-5 b scores 0.06, ranking #5,194 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-5
Kepler-5
- Surface temperature
- 6,297 K (Sun: 5,772 K)
- Mass
- 1.37 M☉
- Radius
- 1.79 R☉
Planetary System
Kepler-5 b is the only planet known to orbit Kepler-5 so far.
Kepler-5 b — Complete Data
| Radius | 15.984 Earth radii (1.426 Jupiter radii) |
|---|---|
| Mass | 670.94 Earth masses (2.111 Jupiter masses) |
| Density | 0.40 g/cm³ (Earth: 5.51) |
| Orbital period | 3.55 days |
| Orbital distance | 0.054 AU |
| Equilibrium temperature | 1,750 K (1,477 °C) |
| Earth Similarity Index | 0.06 |
| Distance from Earth | 2,934.7 light-years (899.8 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2009 |
Data: NASA Exoplanet Archive, last updated 2015-10-07. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-5 b
Is Kepler-5 b habitable?
No — Kepler-5 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-5 b?
Kepler-5 b is about 2,935 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 51,650,720 years to get there.
How big is Kepler-5 b compared to Earth?
Kepler-5 b has 15.98 times the radius of Earth and about 671 times its mass.
How long is a year on Kepler-5 b?
One orbit around Kepler-5 takes 3.5 Earth days — short enough that 103 of its years would fit into one Earth year.
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