TOI-908 b
TOI-908 b is a sub-Neptune orbiting the G V star TOI-908 in the constellation Mensa. It lies about 573 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-908 b?
TOI-908 b has a radius of 3.19 times that of Earth. Its mass is 16.1 times that of Earth, giving it a density of 2.74 g/cm³ — between that of rocky and gaseous planets.
Is TOI-908 b in the Habitable Zone?
TOI-908 b orbits inside the inner edge of the habitable zone of TOI-908. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-908: 0.738–1.746 AU (conservative: 0.935–1.656 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-908 b
The equilibrium temperature of TOI-908 b is about 1,317 K (1,044 °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 80.88 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-908 b — one full orbit around TOI-908 — lasts 3.18 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.042 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.13).
How Was TOI-908 b Discovered?
TOI-908 b was discovered in 2023 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-908 b?
TOI-908 b is 573.2 light-years (175.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1453. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 10,088,320 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-908 b scores 0.20, ranking #3,837 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-908
TOI-908
- Spectral type
- G V
- Surface temperature
- 5,626 K (Sun: 5,772 K)
- Mass
- 0.95 M☉
- Radius
- 1.03 R☉
- Age
- 4.6 billion years (Sun: 4.6)
Planetary System
TOI-908 b is the only planet known to orbit TOI-908 so far.
TOI-908 b — Complete Data
| Radius | 3.186 Earth radii (0.284 Jupiter radii) |
|---|---|
| Mass | 16.14 Earth masses (0.051 Jupiter masses) |
| Density | 2.74 g/cm³ (Earth: 5.51) |
| Orbital period | 3.18 days |
| Orbital distance | 0.042 AU |
| Eccentricity | 0.132 |
| Equilibrium temperature | 1,317 K (1,044 °C) |
| Stellar irradiation | 80.88× Earth |
| Earth Similarity Index | 0.20 |
| Distance from Earth | 573.2 light-years (175.7 parsecs) |
| Constellation | Mensa |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-07-10. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-908 b
Is TOI-908 b habitable?
No — TOI-908 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-908 b?
TOI-908 b is about 573 light-years from Earth in the constellation Mensa. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 10,088,320 years to get there.
How big is TOI-908 b compared to Earth?
TOI-908 b has 3.19 times the radius of Earth and about 16.1 times its mass.
How long is a year on TOI-908 b?
One orbit around TOI-908 takes 3.2 Earth days — short enough that 115 of its years would fit into one Earth year.
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