Habitable-zone candidate
TOI-700
TESS's first Earth-sized HZ planet — and TOI-700 e found in 2023.
- Planets
- 4
- Distance
- 101.5 ly
- Host
- M-type
About TOI-700
Discovery
Discovered by NASA's TESS mission and announced in January 2020, TOI-700 d was TESS's first Earth-sized habitable-zone planet; a fourth planet, TOI-700 e, was confirmed in 2023 also within the habitable zone.
Why it matters
TOI-700 is one of the few habitable-zone systems with a host star bright enough for serious atmospheric follow-up — the kind of target TESS was built to deliver to JWST and the next generation of telescopes.
Current research
Ground-based radial-velocity teams are still refining planet masses, and TOI-700 d/e are on shortlists for future habitable-world atmospheric searches.
Comparable to
An M-dwarf miniature solar system 101 light-years away, with two roughly Earth-sized worlds straddling the inner and outer edges of the habitable zone.
System geometry
At a glance
- Hostname
- TOI-700
- Spectral type
- M2.5 V
- Distance
- 101.5 ly · 31.13 pc
- Stellar mass
- 0.41 M☉
- Stellar radius
- 0.42 R☉
- Luminosity
- 0.023 L☉
- Effective temp
- 3459 K
- Confirmed planets
- 4
- Habitable zone
- 0.144 – 0.207 AU
Top-down orbital diagram
Orbits to scale within this system. Dashed green = habitable-zone edges.
Planet positions are illustrative (evenly spaced in phase). For live motion see the 3D scene.
The planets
4 confirmed.
Rocky world
TOI-700 b
- Orbit
- 0.068 AU
- Period
- 9.98 days
- Radius
- 0.91 R⊕
- Mass
- 0.70 M⊕
- Eq. temperature
- 417 K
- Eccentricity
- 0.075
- Discovered
- 2020 · Transit
Sub-Neptune
TOI-700 c
- Orbit
- 0.093 AU
- Period
- 16.05 days
- Radius
- 2.60 R⊕
- Mass
- 7.27 M⊕
- Eq. temperature
- 356 K
- Eccentricity
- 0.068
- Discovered
- 2020 · Transit
Rocky world
TOI-700 e
- Orbit
- 0.134 AU
- Period
- 27.81 days
- Radius
- 0.95 R⊕
- Mass
- 0.82 M⊕
- Eq. temperature
- 273 K
- Eccentricity
- 0.059
- Discovered
- 2023 · Transit
Rocky world
TOI-700 d
- Orbit
- 0.163 AU
- Period
- 37.42 days
- Radius
- 1.07 R⊕
- Mass
- 1.25 M⊕
- Eq. temperature
- 269 K
- Eccentricity
- 0.042
- Discovered
- 2020 · Transit
Compared to our Solar System
Each row shows the closest Solar-System analog by radius (log-space). Earth is pinned at the bottom as the constant frame of reference.
| Planet | Radius (R⊕) | Mass (M⊕) | Orbit (AU) | Period (days) | Eq temp (K) | Solar analog |
|---|---|---|---|---|---|---|
| TOI-700 b | 0.91 | 0.70 | 0.068 | 9.98 | 417 | Venus |
| TOI-700 c | 2.60 | 7.27 | 0.093 | 16.05 | 356 | Neptune |
| TOI-700 e | 0.95 | 0.82 | 0.134 | 27.81 | 273 | Venus |
| TOI-700 d | 1.07 | 1.25 | 0.163 | 37.42 | 269 | Earth |
| Earth (reference) | 1.00 | 1.00 | 1.000 | 365.25 | 255 | — |
Research status
◇ JWST observation status
1 planet has confirmed JWST observation time across Cycles 1–3.
- TOI-700 d
JWST programs include transit spectroscopy, thermal phase curves, and direct imaging coronagraph observations depending on planet class.
Discovery timeline
- 2020
3 planets: b, c, d
via Transit
- 2023
TOI-700 e
via Transit
If you liked this
Other systems in the same theme:
TRAPPIST-1
7 planets · 40.5 ly · M8.0 V
Seven Earth-sized planets around an ultracool dwarf — three in the habitable zone.
Proxima Centauri
2 planets · 4.2 ly · M5.5 V
Our nearest stellar neighbour hosts a potentially habitable terrestrial world.
Kepler-186
5 planets · 579.2 ly · M1
First Earth-sized planet found in another star's habitable zone (2014).
Related reading
Articles mentioning TOI-700:
Experience it
See TOI-700 in interactive 3D
Fly through the system, click any planet, watch orbits play out at 100× speed.
▶ Launch 3D scene