TOI-700 d
TOI-700 d 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. 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-700 d?
TOI-700 d has a radius of 1.07 times that of Earth.
Is TOI-700 d in the Habitable Zone?
TOI-700 d orbits inside the conservative habitable zone of TOI-700 — 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-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 d
TOI-700 d receives 0.85 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-700 d — one full orbit around TOI-700 — lasts 37.4 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.163 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.042).
How Was TOI-700 d Discovered?
TOI-700 d 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 d?
TOI-700 d 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 d scores 0.94, ranking #2 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 d is one of 4 known planets in the TOI-700 system. Its siblings:
TOI-700 d — Complete Data
| Radius | 1.073 Earth radii (0.096 Jupiter radii) |
|---|---|
| Orbital period | 37.42 days |
| Orbital distance | 0.163 AU |
| Eccentricity | 0.042 |
| Stellar irradiation | 0.85× Earth |
| Earth Similarity Index | 0.94 |
| 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 d
Is TOI-700 d habitable?
TOI-700 d orbits within the habitable zone of TOI-700, 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-700 d?
TOI-700 d 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 d compared to Earth?
TOI-700 d has 1.07 times the radius of Earth.
How long is a year on TOI-700 d?
One orbit around TOI-700 takes 37.4 Earth days.
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