K2-24 c
K2-24 c is a cold gas giant orbiting K2-24 in the constellation Scorpius. It lies about 556 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-24 c?
K2-24 c has a radius of 7.93 times that of Earth, or 0.71 times the radius of Jupiter. Its mass is 16.4 times that of Earth, giving it a density of 0.18 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is K2-24 c in the Habitable Zone?
K2-24 c orbits inside the inner edge of the habitable zone of K2-24. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of K2-24: 0.876–2.067 AU (conservative: 1.110–1.960 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on K2-24 c
The equilibrium temperature of K2-24 c is about 591 K (318 °C) — hotter than anywhere on Earth. 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 K2-24 c — one full orbit around K2-24 — lasts 42.3 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.262 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.028).
How Was K2-24 c Discovered?
K2-24 c 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 K2-24 c?
K2-24 c is 556.3 light-years (170.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1470. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 9,790,880 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. K2-24 c scores 0.15, ranking #4,185 of 5,565 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-24
K2-24
- Surface temperature
- 5,726 K (Sun: 5,772 K)
- Mass
- 1.09 M☉
- Radius
- 1.19 R☉
- Age
- 4.9 billion years (Sun: 4.6)
The K2-24 Planetary System
K2-24 c is one of 2 known planets in the K2-24 system. Its siblings:
- K2-24 b (Neptune-like)
K2-24 c — Complete Data
| Radius | 7.930 Earth radii (0.707 Jupiter radii) |
|---|---|
| Mass | 16.40 Earth masses (0.052 Jupiter masses) |
| Density | 0.18 g/cm³ (Earth: 5.51) |
| Orbital period | 42.35 days |
| Orbital distance | 0.262 AU |
| Eccentricity | 0.028 |
| Equilibrium temperature | 591 K (318 °C) |
| Earth Similarity Index | 0.15 |
| Distance from Earth | 556.3 light-years (170.6 parsecs) |
| Constellation | Scorpius |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2026-08-06. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-24 c
Is K2-24 c habitable?
No — K2-24 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is K2-24 c?
K2-24 c is about 556 light-years from Earth in the constellation Scorpius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 9,790,880 years to get there.
How big is K2-24 c compared to Earth?
K2-24 c has 7.93 times the radius of Earth and about 16.4 times its mass.
How long is a year on K2-24 c?
One orbit around K2-24 takes 42.3 Earth days.
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