TOI-904 c
TOI-904 c 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. It orbits within the habitable zone of its star — the region where liquid water could exist on a planet's surface.
How Big Is TOI-904 c?
TOI-904 c has a radius of 2.17 times that of Earth.
Is TOI-904 c in the Habitable Zone?
TOI-904 c orbits inside the conservative habitable zone of TOI-904 — the region where a rocky planet could sustain liquid water on its surface. This makes it one of the most interesting known exoplanets in the search for life.
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.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Temperature on TOI-904 c
The equilibrium temperature of TOI-904 c is about 217 K (-56 °C) — well below freezing. 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 c — one full orbit around TOI-904 — lasts 84.0 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.312 AU — closer to its star than Mercury is to the Sun.
How Was TOI-904 c Discovered?
TOI-904 c 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 c?
TOI-904 c 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 c scores 0.66, ranking #87 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 c is one of 2 known planets in the TOI-904 system. Its siblings:
- TOI-904 b (Mini Neptune)
TOI-904 c — Complete Data
| Radius | 2.167 Earth radii (0.193 Jupiter radii) |
|---|---|
| Orbital period | 84.00 days |
| Orbital distance | 0.312 AU |
| Equilibrium temperature | 217 K (-56 °C) |
| Earth Similarity Index | 0.66 |
| 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 c
Is TOI-904 c habitable?
TOI-904 c orbits within the habitable zone of TOI-904, the region where liquid water could exist on a planet's surface. It sits in the conservative habitable zone — the most promising region for habitability. Whether it is actually habitable depends on its atmosphere and composition, which remain unknown.
How far away is TOI-904 c?
TOI-904 c 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 c compared to Earth?
TOI-904 c has 2.17 times the radius of Earth.
How long is a year on TOI-904 c?
One orbit around TOI-904 takes 84.0 Earth days.
Explore TOI-904 c in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
