CoRoT-4 b
CoRoT-4 b is a hot Jupiter orbiting CoRoT-4 in the constellation Monoceros. It lies about 2,369 light-years from Earth and was discovered in 2008 using the transit method.
How Big Is CoRoT-4 b?
CoRoT-4 b has a radius of 13.34 times that of Earth, or 1.19 times the radius of Jupiter. Its mass is 229 times that of Earth, giving it a density of 0.53 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is CoRoT-4 b in the Habitable Zone?
CoRoT-4 b orbits inside the inner edge of the habitable zone of CoRoT-4. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of CoRoT-4: 0.983–2.294 AU (conservative: 1.245–2.174 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on CoRoT-4 b
The equilibrium temperature of CoRoT-4 b is about 1,074 K (801 °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 CoRoT-4 b — one full orbit around CoRoT-4 — lasts 9.20 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.090 AU — closer to its star than Mercury is to the Sun.
How Was CoRoT-4 b Discovered?
CoRoT-4 b was discovered in 2008 using the transit method, with observations from CoRoT.
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 CoRoT-4 b?
CoRoT-4 b is 2,369.2 light-years (726.4 parsecs) from Earth. Light arriving here tonight left the planet about 2,369 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 41,697,920 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. CoRoT-4 b scores 0.07, ranking #4,867 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: CoRoT-4
CoRoT-4
- Surface temperature
- 6,190 K (Sun: 5,772 K)
- Mass
- 1.16 M☉
- Radius
- 1.17 R☉
- Age
- 1.0 billion years (Sun: 4.6)
Planetary System
CoRoT-4 b is the only planet known to orbit CoRoT-4 so far.
CoRoT-4 b — Complete Data
| Radius | 13.340 Earth radii (1.190 Jupiter radii) |
|---|---|
| Mass | 228.83 Earth masses (0.720 Jupiter masses) |
| Density | 0.53 g/cm³ (Earth: 5.51) |
| Orbital period | 9.20 days |
| Orbital distance | 0.090 AU |
| Equilibrium temperature | 1,074 K (801 °C) |
| Earth Similarity Index | 0.07 |
| Distance from Earth | 2,369.2 light-years (726.4 parsecs) |
| Constellation | Monoceros |
| Discovery method | Transit |
| Discovery facility | CoRoT |
| Discovery year | 2008 |
Data: NASA Exoplanet Archive, last updated 2025-06-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About CoRoT-4 b
Is CoRoT-4 b habitable?
No — CoRoT-4 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is CoRoT-4 b?
CoRoT-4 b is about 2,369 light-years from Earth in the constellation Monoceros. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 41,697,920 years to get there.
How big is CoRoT-4 b compared to Earth?
CoRoT-4 b has 13.34 times the radius of Earth and about 229 times its mass.
How long is a year on CoRoT-4 b?
One orbit around CoRoT-4 takes 9.2 Earth days — short enough that 40 of its years would fit into one Earth year.
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