K2-180 b
K2-180 b is a super-Earth orbiting K2-180 in the constellation Cancer. It lies about 665 light-years from Earth and was discovered in 2018 using the transit method.
How Big Is K2-180 b?
K2-180 b has a radius of 2.47 times that of Earth. Its mass is 11.4 times that of Earth, giving it a density of 4.16 g/cm³ — between that of rocky and gaseous planets.
Is K2-180 b in the Habitable Zone?
K2-180 b orbits inside the inner edge of the habitable zone of K2-180. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-180: 0.478–1.139 AU (conservative: 0.605–1.080 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on K2-180 b
The equilibrium temperature of K2-180 b is about 798 K (524 °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 K2-180 b — one full orbit around K2-180 — lasts 8.87 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.076 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.08).
How Was K2-180 b Discovered?
K2-180 b was discovered in 2018 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 K2-180 b?
K2-180 b is 665.0 light-years (203.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1361. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 11,704,000 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. K2-180 b scores 0.25, ranking #3,133 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-180
K2-180
- Surface temperature
- 5,365 K (Sun: 5,772 K)
- Mass
- 0.74 M☉
- Radius
- 0.72 R☉
- Luminosity
- 0.3860 L☉
- Age
- 7.5 billion years (Sun: 4.6)
Planetary System
K2-180 b is the only planet known to orbit K2-180 so far.
K2-180 b — Complete Data
| Radius | 2.466 Earth radii (0.220 Jupiter radii) |
|---|---|
| Mass | 11.41 Earth masses (0.036 Jupiter masses) |
| Density | 4.16 g/cm³ (Earth: 5.51) |
| Orbital period | 8.87 days |
| Orbital distance | 0.076 AU |
| Eccentricity | 0.075 |
| Equilibrium temperature | 798 K (524 °C) |
| Earth Similarity Index | 0.25 |
| Distance from Earth | 665.0 light-years (203.9 parsecs) |
| Constellation | Cancer |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2024-11-20. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-180 b
Is K2-180 b habitable?
No — K2-180 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-180 b?
K2-180 b is about 665 light-years from Earth in the constellation Cancer. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 11,704,000 years to get there.
How big is K2-180 b compared to Earth?
K2-180 b has 2.47 times the radius of Earth and about 11.4 times its mass.
How long is a year on K2-180 b?
One orbit around K2-180 takes 8.9 Earth days — short enough that 41 of its years would fit into one Earth year.
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