Host star — TOI-700
- Spectral type
- M2.5 V
- Temperature
- 3,459 K
- Radius
- 0.42 R☉
- Mass
- 0.41 M☉
- Luminosity
- 0.023 L☉
- Distance
- 31.1 pc (102 ly)
Red dwarf — the most common type of star. Cool and small.
Very cool — a faint red dwarf.
TOI-700 d
Orbits TOI-700 · 102 light-years from Earth
RockyTransit2020ESI 92 · Very Earth-like
Radius
1.07×
Earth
Mass
1.3×
Earth
Year
37d
Temp
269 K
-4°C
Gravity
1.1×
Earth
Distance
102
ly
Could life exist here?
AI analysisTOI-700 d is a rocky world only 7 percent larger than Earth, orbiting a cool red dwarf star 102 light-years away. Its equilibrium temperature of 269 Kelvin places it in the habitable zone—warmer than Mars but cooler than Earth's average, suggesting liquid water could exist on its surface if the atmosphere is right. The planet's mass of 1.25 Earth masses and density of 5.56 g/cm³ indicate a composition similar to our own world, making it genuinely Earth-like in structure. However, the planet likely experiences tidal locking, with one face perpetually facing its dim star, which would create extreme temperature gradients and complicate habitability. The habitable zone of such a faint star is very close in—the planet orbits every 37 days at just 0.163 AU—raising questions about atmospheric retention and long-term stability. What makes TOI-700 d particularly compelling is that it was discovered by NASA's TESS mission and remains one of the most Earth-like exoplanets known, offering an exceptional target for future telescope observations to search for biosignatures.
What it would be like
TOI-700 d is a rocky world, potentially similar in composition to Earth or Mars — a solid surface you could, in theory, stand on.
Surface gravity is about 1.1g — noticeably heavier what you're used to on Earth.
With an equilibrium temperature around -4°C, this planet sits in the temperature range where liquid water could potentially exist on the surface — a key ingredient for life as we know it.
An orbital period of 37 days makes the year 9.8× shorter than Earth's. You'd celebrate your birthday more often here.
Earth comparison
Logarithmic bars so Jupiter-class planets fit the same scale as Earth-size worlds.
Radius1.07R⊕
1/25×Earth = 125×
Mass1.25M⊕
1/10000×Earth = 110000×
Surface gravity1.09g
1/100×Earth = 1100×
Equilibrium temp269 K(-4°C)
0 KEarth 255 K2500 K
Side-by-side with Earth
Temperature in context
Liquid N₂Mars avgEarth eq.Earth sfc.Boiling H₂OVenus
Discovery & orbit
- Method
- Transit
- Year
- 2020
- Facility
- Transiting Exoplanet Survey Satellite (TESS)
- Semi-major axis
- 0.1633 AU
- Period
- 37.42 days
- Eccentricity
- 0.0420
- Density
- 5.56 g/cm³
Detected by measuring the tiny dip in starlight as the planet crosses in front of its star.
Mildly elliptical — similar to most Solar System planets.
Rocky composition likely. Earth is 5.51 g/cm³.
Discovered via · Transit
Tiny dip in starlight as the planet crosses in front of its star
A transit photometer watches a star nonstop and measures its brightness to ~0.01%. When a planet passes between us and the star, the star dims briefly — the deeper the dip, the bigger the planet. This is how Kepler and TESS found most known exoplanets.
- Overall share
- ~75% of all confirmed worlds
- Best for
- Earth-to-Neptune-sized planets on short orbits
Orbital Animation
TOI-700TOI-700 dOrbitHabitable zone
Drag to rotate · scroll to zoomSemi-major axis: 0.163 AUEccentricity: 0.0420Period: 37.4 days
Hertzsprung–Russell Diagram
Where this host star sits among … exoplanet host stars. The main sequence band runs diagonally — giants and supergiants sit above, white dwarfs below.
OBAFGKMCurrent star
How far is 102 light-years?
- A light beam leaving Earth right now would arrive in 102 years.
- At Voyager 1's speed (17 km/s), the trip would take approximately 1.8 million years.
- A radio signal sent today would arrive in 101.5 years — and the reply wouldn't come back for twice that.
Earth Similarity Index
92/1000 — Nothing like Earth100 — Identical to Earth
ESI combines radius similarity and equilibrium temperature similarity. Earth = 100. Mars ≈ 73. Venus ≈ 44. This score reflects two physical parameters only — not atmosphere, water, or magnetic field.