TOI-3785 b
TOI-3785 b is a Neptune-like planet orbiting the M2 V star TOI-3785 in the constellation Ursa Major. It lies about 260 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-3785 b?
TOI-3785 b has a radius of 5.14 times that of Earth. Its mass is 15.0 times that of Earth, giving it a density of 0.61 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-3785 b in the Habitable Zone?
TOI-3785 b orbits inside the inner edge of the habitable zone of TOI-3785. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-3785: 0.157–0.405 AU (conservative: 0.198–0.384 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-3785 b
The equilibrium temperature of TOI-3785 b is about 582 K (309 °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 19.10 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-3785 b — one full orbit around TOI-3785 — lasts 4.67 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.043 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.11).
How Was TOI-3785 b Discovered?
TOI-3785 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-3785 b?
TOI-3785 b is 260.2 light-years (79.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1766. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 4,579,520 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-3785 b scores 0.20, ranking #3,859 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-3785
TOI-3785
- Spectral type
- M2 V
- Surface temperature
- 3,576 K (Sun: 5,772 K)
- Mass
- 0.52 M☉
- Radius
- 0.50 R☉
- Luminosity
- 0.0367 L☉
- Age
- 8.0 billion years (Sun: 4.6)
Planetary System
TOI-3785 b is the only planet known to orbit TOI-3785 so far.
TOI-3785 b — Complete Data
| Radius | 5.140 Earth radii (0.459 Jupiter radii) |
|---|---|
| Mass | 14.95 Earth masses (0.047 Jupiter masses) |
| Density | 0.61 g/cm³ (Earth: 5.51) |
| Orbital period | 4.67 days |
| Orbital distance | 0.043 AU |
| Eccentricity | 0.110 |
| Equilibrium temperature | 582 K (309 °C) |
| Stellar irradiation | 19.10× Earth |
| Earth Similarity Index | 0.20 |
| Distance from Earth | 260.2 light-years (79.8 parsecs) |
| Constellation | Ursa Major |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-07-21. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-3785 b
Is TOI-3785 b habitable?
No — TOI-3785 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-3785 b?
TOI-3785 b is about 260 light-years from Earth in the constellation Ursa Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 4,579,520 years to get there.
How big is TOI-3785 b compared to Earth?
TOI-3785 b has 5.14 times the radius of Earth and about 15.0 times its mass.
How long is a year on TOI-3785 b?
One orbit around TOI-3785 takes 4.7 Earth days — short enough that 78 of its years would fit into one Earth year.
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