TOI-431 b
TOI-431 b is a lava world orbiting TOI-431 in the constellation Lepus. It lies about 106 light-years from Earth and was discovered in 2021 using the transit method.
How Big Is TOI-431 b?
TOI-431 b has a radius of 1.28 times that of Earth. Its mass is 3.1 times that of Earth, giving it a density of 8.00 g/cm³ — comparable to rocky planets like Earth (5.51 g/cm³).
Is TOI-431 b in the Habitable Zone?
TOI-431 b orbits inside the inner edge of the habitable zone of TOI-431. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-431: 0.406–0.988 AU (conservative: 0.515–0.937 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-431 b
The equilibrium temperature of TOI-431 b is about 1,862 K (1,589 °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-431 b — one full orbit around TOI-431 — lasts just 11.8 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.011 AU — closer to its star than Mercury is to the Sun.
How Was TOI-431 b Discovered?
TOI-431 b was discovered in 2021 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-431 b?
TOI-431 b is 106.2 light-years (32.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1920. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,869,120 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-431 b scores 0.29, ranking #1,936 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-431
TOI-431
- Surface temperature
- 4,850 K (Sun: 5,772 K)
- Mass
- 0.78 M☉
- Radius
- 0.73 R☉
The TOI-431 Planetary System
TOI-431 b is one of 3 known planets in the TOI-431 system. Its siblings:
TOI-431 b — Complete Data
| Radius | 1.280 Earth radii (0.114 Jupiter radii) |
|---|---|
| Mass | 3.07 Earth masses (0.010 Jupiter masses) |
| Density | 8.00 g/cm³ (Earth: 5.51) |
| Orbital period | 0.49 days |
| Orbital distance | 0.011 AU |
| Equilibrium temperature | 1,862 K (1,589 °C) |
| Earth Similarity Index | 0.29 |
| Distance from Earth | 106.2 light-years (32.6 parsecs) |
| Constellation | Lepus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2021-08-16. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-431 b
Is TOI-431 b habitable?
No — TOI-431 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-431 b?
TOI-431 b is about 106 light-years from Earth in the constellation Lepus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,869,120 years to get there.
How big is TOI-431 b compared to Earth?
TOI-431 b has 1.28 times the radius of Earth and about 3.1 times its mass.
How long is a year on TOI-431 b?
One orbit around TOI-431 takes 0.5 Earth days — short enough that 745 of its years would fit into one Earth year.
Explore TOI-431 b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
