Kepler-1978 b
Kepler-1978 b is a mini-Neptune orbiting Kepler-1978 in the constellation Lyra. It lies about 2,823 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is Kepler-1978 b?
Kepler-1978 b has a radius of 2.67 times that of Earth.
Is Kepler-1978 b in the Habitable Zone?
Kepler-1978 b orbits inside the inner edge of the habitable zone of Kepler-1978. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Kepler-1978: 0.497–1.190 AU (conservative: 0.629–1.128 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 ›
Temperature on Kepler-1978 b
The equilibrium temperature of Kepler-1978 b is about 676 K (403 °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. It receives 49.30 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on Kepler-1978 b — one full orbit around Kepler-1978 — lasts 10.8 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.091 AU — closer to its star than Mercury is to the Sun.
How Was Kepler-1978 b Discovered?
Kepler-1978 b was discovered in 2023 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-1978 b?
Kepler-1978 b is 2,822.9 light-years (865.5 parsecs) from Earth. Light arriving here tonight left the planet about 2,823 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 49,683,040 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-1978 b scores 0.24, ranking #3,228 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Kepler-1978
Kepler-1978
- Surface temperature
- 5,251 K (Sun: 5,772 K)
- Mass
- 0.87 M☉
- Radius
- 0.78 R☉
Planetary System
Kepler-1978 b is the only planet known to orbit Kepler-1978 so far.
Kepler-1978 b — Complete Data
| Radius | 2.670 Earth radii (0.238 Jupiter radii) |
|---|---|
| Orbital period | 10.85 days |
| Orbital distance | 0.091 AU |
| Equilibrium temperature | 676 K (403 °C) |
| Stellar irradiation | 49.30× Earth |
| Earth Similarity Index | 0.24 |
| Distance from Earth | 2,822.9 light-years (865.5 parsecs) |
| Constellation | Lyra |
| Discovery method | Transit |
| Discovery facility | Kepler |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2017-05-08. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Kepler-1978 b
Is Kepler-1978 b habitable?
No — Kepler-1978 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Kepler-1978 b?
Kepler-1978 b is about 2,823 light-years from Earth in the constellation Lyra. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 49,683,040 years to get there.
How big is Kepler-1978 b compared to Earth?
Kepler-1978 b has 2.67 times the radius of Earth.
How long is a year on Kepler-1978 b?
One orbit around Kepler-1978 takes 10.8 Earth days — short enough that 34 of its years would fit into one Earth year.
Explore Kepler-1978 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
