TOI-756 b
TOI-756 b is a mini-Neptune orbiting the M1 V star TOI-756 in the constellation Centaurus. It lies about 281 light-years from Earth and was discovered in 2025 using the transit method.
How Big Is TOI-756 b?
TOI-756 b has a radius of 2.81 times that of Earth. Its mass is 9.8 times that of Earth, giving it a density of 2.42 g/cm³ — between that of rocky and gaseous planets.
Is TOI-756 b in the Habitable Zone?
TOI-756 b orbits inside the inner edge of the habitable zone of TOI-756. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-756: 0.165–0.426 AU (conservative: 0.209–0.403 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-756 b
The equilibrium temperature of TOI-756 b is about 934 K (661 °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 127 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-756 b — one full orbit around TOI-756 — lasts just 29.7 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.018 AU — closer to its star than Mercury is to the Sun.
How Was TOI-756 b Discovered?
TOI-756 b was discovered in 2025 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-756 b?
TOI-756 b is 281.1 light-years (86.2 parsecs) from Earth. Light arriving here tonight left the planet around the year 1745. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 4,947,360 years to make the journey.
The Host Star: TOI-756
TOI-756
- Spectral type
- M1 V
- Surface temperature
- 3,657 K (Sun: 5,772 K)
- Mass
- 0.51 M☉
- Radius
- 0.51 R☉
- Luminosity
- 0.0410 L☉
- Age
- 3.2 billion years (Sun: 4.6)
The TOI-756 Planetary System
TOI-756 b is one of 2 known planets in the TOI-756 system. Its siblings:
- TOI-756 c (Cold Gas Giant)
TOI-756 b — Complete Data
| Radius | 2.810 Earth radii (0.251 Jupiter radii) |
|---|---|
| Mass | 9.83 Earth masses (0.031 Jupiter masses) |
| Density | 2.42 g/cm³ (Earth: 5.51) |
| Orbital period | 1.24 days |
| Orbital distance | 0.018 AU |
| Equilibrium temperature | 934 K (661 °C) |
| Stellar irradiation | 127.00× Earth |
| Distance from Earth | 281.1 light-years (86.2 parsecs) |
| Constellation | Centaurus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2025 |
Data: NASA Exoplanet Archive, last updated 2025-11-13. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-756 b
Is TOI-756 b habitable?
No — TOI-756 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-756 b?
TOI-756 b is about 281 light-years from Earth in the constellation Centaurus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 4,947,360 years to get there.
How big is TOI-756 b compared to Earth?
TOI-756 b has 2.81 times the radius of Earth and about 9.8 times its mass.
How long is a year on TOI-756 b?
One orbit around TOI-756 takes 1.2 Earth days — short enough that 295 of its years would fit into one Earth year.
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