Kepler-1708 b
Kepler-1708 b is a cold gas giant orbiting Kepler-1708 in the constellation Cygnus. It lies about 5,436 light-years from Earth and was discovered in 2021 using the transit method. It orbits within the habitable zone of its star — the region where liquid water could exist on a planet's surface.
How Big Is Kepler-1708 b?
Kepler-1708 b has a radius of 9.96 times that of Earth, or 0.89 times the radius of Jupiter. Its mass is 1,462 times that of Earth.
Is Kepler-1708 b in the Habitable Zone?
Kepler-1708 b orbits inside the conservative habitable zone of Kepler-1708 — the region where a rocky planet could sustain liquid water on its surface. This makes it one of the most interesting known exoplanets in the search for life.
Habitable zone of Kepler-1708: 0.904–2.112 AU (conservative: 1.145–2.002 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on Kepler-1708 b
Kepler-1708 b receives 0.56 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Kepler-1708 b — one full orbit around Kepler-1708 — lasts 737.1 Earth days, longer than an Earth year. It orbits at an average distance of 1.640 AU. Its orbit is highly elliptical (eccentricity 0.40), swinging dramatically closer to and farther from its star.
How Was Kepler-1708 b Discovered?
Kepler-1708 b was discovered in 2021 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-1708 b?
Kepler-1708 b is 5,436.0 light-years (1,666.7 parsecs) from Earth. Light arriving here tonight left the planet about 5,436 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 95,673,600 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-1708 b scores 0.40, ranking #478 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-1708
Kepler-1708
- Surface temperature
- 6,157 K (Sun: 5,772 K)
- Mass
- 1.09 M☉
- Radius
- 1.12 R☉
- Luminosity
- 1.5205 L☉
- Age
- 3.2 billion years (Sun: 4.6)
Planetary System
Kepler-1708 b is the only planet known to orbit Kepler-1708 so far.
Kepler-1708 b — Complete Data
| Radius | 9.960 Earth radii (0.889 Jupiter radii) |
|---|---|
| Mass | 1,462.01 Earth masses (4.600 Jupiter masses) |
| Orbital period | 737.11 days |
| Orbital distance | 1.640 AU |
| Eccentricity | 0.400 |
| Stellar irradiation | 0.56× Earth |
| Earth Similarity Index | 0.40 |
| Distance from Earth | 5,436.0 light-years (1,666.7 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2022-01-10. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-1708 b
Is Kepler-1708 b habitable?
Kepler-1708 b orbits within the habitable zone of Kepler-1708, the region where liquid water could exist on a planet's surface. It sits in the conservative habitable zone — the most promising region for habitability. Whether it is actually habitable depends on its atmosphere and composition, which remain unknown.
How far away is Kepler-1708 b?
Kepler-1708 b is about 5,436 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 95,673,600 years to get there.
How big is Kepler-1708 b compared to Earth?
Kepler-1708 b has 9.96 times the radius of Earth and about 1,462 times its mass.
How long is a year on Kepler-1708 b?
One orbit around Kepler-1708 takes 737.1 Earth days.
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