TOI-4342 c
TOI-4342 c is a mini-Neptune orbiting the M0 V star TOI-4342 in the constellation Octans. It lies about 201 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-4342 c?
TOI-4342 c has a radius of 2.35 times that of Earth. Its mass is 4.8 times that of Earth, giving it a density of 2.01 g/cm³ — between that of rocky and gaseous planets.
Is TOI-4342 c in the Habitable Zone?
TOI-4342 c orbits inside the inner edge of the habitable zone of TOI-4342. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-4342: 0.223–0.568 AU (conservative: 0.282–0.538 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-4342 c
The equilibrium temperature of TOI-4342 c is about 514 K (241 °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. It receives 11.60 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-4342 c — one full orbit around TOI-4342 — lasts 10.7 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.080 AU — closer to its star than Mercury is to the Sun.
How Was TOI-4342 c Discovered?
TOI-4342 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-4342 c?
TOI-4342 c is 200.7 light-years (61.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1826. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,532,320 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-4342 c scores 0.34, ranking #856 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-4342
TOI-4342
- Spectral type
- M0 V
- Surface temperature
- 3,866 K (Sun: 5,772 K)
- Mass
- 0.59 M☉
- Radius
- 0.60 R☉
- Luminosity
- 0.0750 L☉
The TOI-4342 Planetary System
TOI-4342 c is one of 2 known planets in the TOI-4342 system. Its siblings:
- TOI-4342 b (Super Earth)
TOI-4342 c — Complete Data
| Radius | 2.349 Earth radii (0.210 Jupiter radii) |
|---|---|
| Mass | 4.80 Earth masses (0.015 Jupiter masses) |
| Density | 2.01 g/cm³ (Earth: 5.51) |
| Orbital period | 10.69 days |
| Orbital distance | 0.080 AU |
| Equilibrium temperature | 514 K (241 °C) |
| Stellar irradiation | 11.60× Earth |
| Earth Similarity Index | 0.34 |
| Distance from Earth | 200.7 light-years (61.5 parsecs) |
| Constellation | Octans |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2026-02-26. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-4342 c
Is TOI-4342 c habitable?
No — TOI-4342 c orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-4342 c?
TOI-4342 c is about 201 light-years from Earth in the constellation Octans. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,532,320 years to get there.
How big is TOI-4342 c compared to Earth?
TOI-4342 c has 2.35 times the radius of Earth and about 4.8 times its mass.
How long is a year on TOI-4342 c?
One orbit around TOI-4342 takes 10.7 Earth days — short enough that 34 of its years would fit into one Earth year.
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