TOI-2158 b
TOI-2158 b is a hot Jupiter orbiting TOI-2158 in the constellation Hercules. It lies about 647 light-years from Earth and was discovered in 2022 using the transit method.
How Big Is TOI-2158 b?
TOI-2158 b has a radius of 10.08 times that of Earth, or 0.90 times the radius of Jupiter. Its mass is 277 times that of Earth.
Is TOI-2158 b in the Habitable Zone?
TOI-2158 b orbits inside the inner edge of the habitable zone of TOI-2158. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-2158: 0.961–2.270 AU (conservative: 1.217–2.153 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-2158 b
The equilibrium temperature of TOI-2158 b is about 1,173 K (900 °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. It receives 215 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-2158 b — one full orbit around TOI-2158 — lasts 8.60 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.070 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.028).
How Was TOI-2158 b Discovered?
TOI-2158 b was discovered in 2022 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
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 TOI-2158 b?
TOI-2158 b is 647.3 light-years (198.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1379. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 11,392,480 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. TOI-2158 b scores 0.08, ranking #4,577 of 5,565 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-2158
TOI-2158
- Surface temperature
- 5,673 K (Sun: 5,772 K)
- Mass
- 1.12 M☉
- Radius
- 1.32 R☉
- Age
- 7.7 billion years (Sun: 4.6)
The TOI-2158 Planetary System
TOI-2158 b is one of 2 known planets in the TOI-2158 system. Its siblings:
- TOI-2158 c (Cold Gas Giant)
TOI-2158 b — Complete Data
| Radius | 10.077 Earth radii (0.899 Jupiter radii) |
|---|---|
| Mass | 276.51 Earth masses (0.870 Jupiter masses) |
| Orbital period | 8.60 days |
| Orbital distance | 0.070 AU |
| Eccentricity | 0.028 |
| Equilibrium temperature | 1,173 K (900 °C) |
| Stellar irradiation | 215.00× Earth |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 647.3 light-years (198.5 parsecs) |
| Constellation | Hercules |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2026-10-15. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-2158 b
Is TOI-2158 b habitable?
No — TOI-2158 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-2158 b?
TOI-2158 b is about 647 light-years from Earth in the constellation Hercules. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 11,392,480 years to get there.
How big is TOI-2158 b compared to Earth?
TOI-2158 b has 10.08 times the radius of Earth and about 277 times its mass.
How long is a year on TOI-2158 b?
One orbit around TOI-2158 takes 8.6 Earth days — short enough that 42 of its years would fit into one Earth year.
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