TOI-700 b
TOI-700 b is a terrestrial planet orbiting the M2.5 V star TOI-700 in the constellation Dorado. It lies about 102 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is TOI-700 b?
TOI-700 b has a radius of 0.91 times that of Earth.
Is TOI-700 b in the Habitable Zone?
TOI-700 b orbits inside the inner edge of the habitable zone of TOI-700. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-700: 0.124–0.322 AU (conservative: 0.157–0.305 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-700 b
TOI-700 b receives 4.98 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-700 b — one full orbit around TOI-700 — lasts 9.98 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.068 AU — closer to its star than Mercury is to the Sun. Its orbit is mildly elliptical (eccentricity 0.08).
How Was TOI-700 b Discovered?
TOI-700 b was discovered in 2020 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-700 b?
TOI-700 b is 101.5 light-years (31.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1925. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,786,400 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-700 b scores 0.53, ranking #222 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-700
TOI-700
- Spectral type
- M2.5 V
- Surface temperature
- 3,459 K (Sun: 5,772 K)
- Mass
- 0.42 M☉
- Radius
- 0.42 R☉
- Luminosity
- 0.0229 L☉
The TOI-700 Planetary System
TOI-700 b is one of 4 known planets in the TOI-700 system. Its siblings:
TOI-700 b — Complete Data
| Radius | 0.914 Earth radii (0.082 Jupiter radii) |
|---|---|
| Orbital period | 9.98 days |
| Orbital distance | 0.068 AU |
| Eccentricity | 0.075 |
| Stellar irradiation | 4.98× Earth |
| Earth Similarity Index | 0.53 |
| Distance from Earth | 101.5 light-years (31.1 parsecs) |
| Constellation | Dorado |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2023-01-18. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-700 b
Is TOI-700 b habitable?
No — TOI-700 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-700 b?
TOI-700 b is about 102 light-years from Earth in the constellation Dorado. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,786,400 years to get there.
How big is TOI-700 b compared to Earth?
TOI-700 b has 0.91 times the radius of Earth.
How long is a year on TOI-700 b?
One orbit around TOI-700 takes 10.0 Earth days — short enough that 37 of its years would fit into one Earth year.
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