K2-79 b
K2-79 b is a Neptune-like planet orbiting the G1 star K2-79 in the constellation Taurus. It lies about 835 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-79 b?
K2-79 b has a radius of 4.15 times that of Earth. Its mass is 5.9 times that of Earth, giving it a density of 0.48 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is K2-79 b in the Habitable Zone?
K2-79 b orbits inside the inner edge of the habitable zone of K2-79. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-79: 0.988–2.322 AU (conservative: 1.252–2.201 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on K2-79 b
The equilibrium temperature of K2-79 b is about 1,033 K (760 °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 K2-79 b — one full orbit around K2-79 — lasts 11.0 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.099 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.032).
How Was K2-79 b Discovered?
K2-79 b was discovered in 2016 using the transit method, with observations from K2.
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 K2-79 b?
K2-79 b is 835.0 light-years (256.0 parsecs) from Earth. Light arriving here tonight left the planet around the year 1191. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 14,696,000 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. K2-79 b scores 0.18, ranking #4,018 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-79
K2-79
- Spectral type
- G1
- Surface temperature
- 5,897 K (Sun: 5,772 K)
- Mass
- 1.06 M☉
- Radius
- 1.27 R☉
- Luminosity
- 1.7600 L☉
- Age
- 6.5 billion years (Sun: 4.6)
Planetary System
K2-79 b is the only planet known to orbit K2-79 so far.
K2-79 b — Complete Data
| Radius | 4.150 Earth radii (0.370 Jupiter radii) |
|---|---|
| Mass | 5.90 Earth masses (0.019 Jupiter masses) |
| Density | 0.48 g/cm³ (Earth: 5.51) |
| Orbital period | 11.00 days |
| Orbital distance | 0.099 AU |
| Eccentricity | 0.032 |
| Equilibrium temperature | 1,033 K (760 °C) |
| Earth Similarity Index | 0.18 |
| Distance from Earth | 835.0 light-years (256.0 parsecs) |
| Constellation | Taurus |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2026-04-16. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-79 b
Is K2-79 b habitable?
No — K2-79 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-79 b?
K2-79 b is about 835 light-years from Earth in the constellation Taurus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 14,696,000 years to get there.
How big is K2-79 b compared to Earth?
K2-79 b has 4.15 times the radius of Earth and about 5.9 times its mass.
How long is a year on K2-79 b?
One orbit around K2-79 takes 11.0 Earth days — short enough that 33 of its years would fit into one Earth year.
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