Kepler-447 b
Kepler-447 b is a hot Jupiter orbiting the G8 V star Kepler-447 in the constellation Draco. It lies about 874 light-years from Earth and was discovered in 2015 using the transit method.
How Big Is Kepler-447 b?
Kepler-447 b has a radius of 18.49 times that of Earth, or 1.65 times the radius of Jupiter. Its mass is 435 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-447 b in the Habitable Zone?
Kepler-447 b orbits inside the inner edge of the habitable zone of Kepler-447. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-447: 0.724–1.720 AU (conservative: 0.917–1.631 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-447 b — one full orbit around Kepler-447 — lasts 7.79 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.077 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.12).
How Was Kepler-447 b Discovered?
Kepler-447 b was discovered in 2015 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-447 b?
Kepler-447 b is 874.2 light-years (268.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1152. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 15,385,920 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-447 b scores 0.06, ranking #5,159 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-447
Kepler-447
- Spectral type
- G8 V
- Surface temperature
- 5,493 K (Sun: 5,772 K)
- Mass
- 1.00 M☉
- Radius
- 1.05 R☉
Planetary System
Kepler-447 b is the only planet known to orbit Kepler-447 so far.
Kepler-447 b — Complete Data
| Radius | 18.490 Earth radii (1.650 Jupiter radii) |
|---|---|
| Mass | 435.41 Earth masses (1.370 Jupiter masses) |
| Density | 0.40 g/cm³ (Earth: 5.51) |
| Orbital period | 7.79 days |
| Orbital distance | 0.077 AU |
| Eccentricity | 0.123 |
| Earth Similarity Index | 0.06 |
| Distance from Earth | 874.2 light-years (268.0 parsecs) |
| Constellation | Draco |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2015 |
Data: NASA Exoplanet Archive, last updated 2015-02-19. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-447 b
Is Kepler-447 b habitable?
No — Kepler-447 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-447 b?
Kepler-447 b is about 874 light-years from Earth in the constellation Draco. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 15,385,920 years to get there.
How big is Kepler-447 b compared to Earth?
Kepler-447 b has 18.49 times the radius of Earth and about 435 times its mass.
How long is a year on Kepler-447 b?
One orbit around Kepler-447 takes 7.8 Earth days — short enough that 47 of its years would fit into one Earth year.
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