Kepler-45 b
Kepler-45 b is a hot Jupiter orbiting the M star Kepler-45 in the constellation Cygnus. It lies about 1,246 light-years from Earth and was discovered in 2011 using the transit method.
How Big Is Kepler-45 b?
Kepler-45 b has a radius of 10.76 times that of Earth, or 0.96 times the radius of Jupiter. Its mass is 160 times that of Earth, giving it a density of 0.80 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is Kepler-45 b in the Habitable Zone?
Kepler-45 b orbits inside the inner edge of the habitable zone of Kepler-45. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-45: 0.196–0.500 AU (conservative: 0.248–0.474 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Kepler-45 b
The equilibrium temperature of Kepler-45 b is about 1,000 K (727 °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-45 b — one full orbit around Kepler-45 — lasts 2.46 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.030 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.11).
How Was Kepler-45 b Discovered?
Kepler-45 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-45 b?
Kepler-45 b is 1,245.7 light-years (381.9 parsecs) from Earth. Light arriving here tonight left the planet about 1,246 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 21,924,320 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-45 b scores 0.10, ranking #4,440 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-45
Kepler-45
- Spectral type
- M
- Surface temperature
- 3,820 K (Sun: 5,772 K)
- Mass
- 0.59 M☉
- Radius
- 0.55 R☉
- Age
- 0.5 billion years (Sun: 4.6)
Planetary System
Kepler-45 b is the only planet known to orbit Kepler-45 so far.
Kepler-45 b — Complete Data
| Radius | 10.760 Earth radii (0.960 Jupiter radii) |
|---|---|
| Mass | 160.50 Earth masses (0.505 Jupiter masses) |
| Density | 0.80 g/cm³ (Earth: 5.51) |
| Orbital period | 2.46 days |
| Orbital distance | 0.030 AU |
| Eccentricity | 0.110 |
| Equilibrium temperature | 1,000 K (727 °C) |
| Earth Similarity Index | 0.10 |
| Distance from Earth | 1,245.7 light-years (381.9 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-45 b
Is Kepler-45 b habitable?
No — Kepler-45 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-45 b?
Kepler-45 b is about 1,246 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 21,924,320 years to get there.
How big is Kepler-45 b compared to Earth?
Kepler-45 b has 10.76 times the radius of Earth and about 160 times its mass.
How long is a year on Kepler-45 b?
One orbit around Kepler-45 takes 2.5 Earth days — short enough that 149 of its years would fit into one Earth year.
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