TOI-4308 b
TOI-4308 b is a mini-Neptune orbiting TOI-4308 in the constellation Grus. It lies about 355 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-4308 b?
TOI-4308 b has a radius of 2.42 times that of Earth.
Is TOI-4308 b in the Habitable Zone?
The position of TOI-4308 b relative to the habitable zone of TOI-4308 cannot be precisely determined from the available orbital data.
Habitable zone of TOI-4308: 0.505–1.211 AU (conservative: 0.640–1.148 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on TOI-4308 b
The equilibrium temperature of TOI-4308 b is about 763 K (490 °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 TOI-4308 b — one full orbit around TOI-4308 — lasts 9.15 Earth days, shorter than Mercury's 88-day year.
How Was TOI-4308 b Discovered?
TOI-4308 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-4308 b?
TOI-4308 b is 355.3 light-years (108.9 parsecs) from Earth. Light arriving here tonight left the planet around the year 1671. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,253,280 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-4308 b scores 0.25, ranking #2,995 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-4308
TOI-4308
- Surface temperature
- 5,243 K (Sun: 5,772 K)
- Mass
- 0.90 M☉
- Radius
- 0.79 R☉
Planetary System
TOI-4308 b is the only planet known to orbit TOI-4308 so far.
TOI-4308 b — Complete Data
| Radius | 2.419 Earth radii (0.216 Jupiter radii) |
|---|---|
| Orbital period | 9.15 days |
| Equilibrium temperature | 763 K (490 °C) |
| Earth Similarity Index | 0.25 |
| Distance from Earth | 355.3 light-years (108.9 parsecs) |
| Constellation | Grus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-05-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-4308 b
Is TOI-4308 b habitable?
TOI-4308 b is not known to orbit within the habitable zone of TOI-4308, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is TOI-4308 b?
TOI-4308 b is about 355 light-years from Earth in the constellation Grus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,253,280 years to get there.
How big is TOI-4308 b compared to Earth?
TOI-4308 b has 2.42 times the radius of Earth.
How long is a year on TOI-4308 b?
One orbit around TOI-4308 takes 9.2 Earth days — short enough that 40 of its years would fit into one Earth year.
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