TOI-904 b
TOI-904 b is a mini-Neptune orbiting TOI-904 in the constellation Mensa. It lies about 150 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-904 b?
TOI-904 b has a radius of 2.43 times that of Earth.
Is TOI-904 b in the Habitable Zone?
TOI-904 b orbits inside the inner edge of the habitable zone of TOI-904. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-904: 0.184–0.471 AU (conservative: 0.233–0.447 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-904 b
The equilibrium temperature of TOI-904 b is about 429 K (156 °C) — hotter than anywhere on Earth. 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-904 b — one full orbit around TOI-904 — lasts 10.9 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.056 AU — closer to its star than Mercury is to the Sun.
How Was TOI-904 b Discovered?
TOI-904 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-904 b?
TOI-904 b is 150.3 light-years (46.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1876. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 2,645,280 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-904 b scores 0.31, ranking #1,173 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-904
TOI-904
- Surface temperature
- 3,770 K (Sun: 5,772 K)
- Mass
- 0.56 M☉
- Radius
- 0.53 R☉
- Luminosity
- 0.0510 L☉
- Age
- 1.5 billion years (Sun: 4.6)
The TOI-904 Planetary System
TOI-904 b is one of 2 known planets in the TOI-904 system. Its siblings:
- TOI-904 c (Mini Neptune)
TOI-904 b — Complete Data
| Radius | 2.426 Earth radii (0.216 Jupiter radii) |
|---|---|
| Orbital period | 10.88 days |
| Orbital distance | 0.056 AU |
| Equilibrium temperature | 429 K (156 °C) |
| Earth Similarity Index | 0.31 |
| Distance from Earth | 150.3 light-years (46.1 parsecs) |
| Constellation | Mensa |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2024-03-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-904 b
Is TOI-904 b habitable?
No — TOI-904 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-904 b?
TOI-904 b is about 150 light-years from Earth in the constellation Mensa. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 2,645,280 years to get there.
How big is TOI-904 b compared to Earth?
TOI-904 b has 2.43 times the radius of Earth.
How long is a year on TOI-904 b?
One orbit around TOI-904 takes 10.9 Earth days — short enough that 34 of its years would fit into one Earth year.
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