K2-275 c
K2-275 c is a mini-Neptune orbiting K2-275 in the constellation Cancer. It lies about 403 light-years from Earth and was discovered in 2018 using the transit method.
How Big Is K2-275 c?
K2-275 c has a radius of 2.21 times that of Earth.
Is K2-275 c in the Habitable Zone?
K2-275 c orbits inside the inner edge of the habitable zone of K2-275. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-275: 0.382–0.930 AU (conservative: 0.484–0.882 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on K2-275 c
The equilibrium temperature of K2-275 c is about 653 K (380 °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 K2-275 c — one full orbit around K2-275 — lasts 8.44 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.088 AU — closer to its star than Mercury is to the Sun.
How Was K2-275 c Discovered?
K2-275 c 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 K2-275 c?
K2-275 c is 402.6 light-years (123.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1624. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 7,085,760 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. K2-275 c scores 0.28, ranking #2,138 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-275
K2-275
- Surface temperature
- 4,841 K (Sun: 5,772 K)
- Mass
- 0.77 M☉
- Radius
- 0.69 R☉
The K2-275 Planetary System
K2-275 c is one of 2 known planets in the K2-275 system. Its siblings:
- K2-275 b (Mini Neptune)
K2-275 c — Complete Data
| Radius | 2.210 Earth radii (0.197 Jupiter radii) |
|---|---|
| Orbital period | 8.44 days |
| Orbital distance | 0.088 AU |
| Equilibrium temperature | 653 K (380 °C) |
| Earth Similarity Index | 0.28 |
| Distance from Earth | 402.6 light-years (123.4 parsecs) |
| Constellation | Cancer |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2021-09-20. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-275 c
Is K2-275 c habitable?
No — K2-275 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-275 c?
K2-275 c is about 403 light-years from Earth in the constellation Cancer. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 7,085,760 years to get there.
How big is K2-275 c compared to Earth?
K2-275 c has 2.21 times the radius of Earth.
How long is a year on K2-275 c?
One orbit around K2-275 takes 8.4 Earth days — short enough that 43 of its years would fit into one Earth year.
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