TOI-270 d
TOI-270 d is a mini-Neptune orbiting TOI-270 in the constellation Pictor. It lies about 73 light-years from Earth and was discovered in 2019 using the transit method.
How Big Is TOI-270 d?
TOI-270 d has a radius of 2.00 times that of Earth. Its mass is 4.2 times that of Earth, giving it a density of 2.90 g/cm³ — between that of rocky and gaseous planets.
Is TOI-270 d in the Habitable Zone?
The position of TOI-270 d relative to the habitable zone of TOI-270 cannot be precisely determined from the available orbital data.
Habitable zone of TOI-270: 0.114–0.297 AU (conservative: 0.145–0.281 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-270 d
The equilibrium temperature of TOI-270 d is about 383 K (110 °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.
Orbit and Year Length
A year on TOI-270 d — one full orbit around TOI-270 — lasts 11.4 Earth days, shorter than Mercury's 88-day year. Its orbit is nearly circular (eccentricity 0.007).
How Was TOI-270 d Discovered?
TOI-270 d was discovered in 2019 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-270 d?
TOI-270 d is 73.3 light-years (22.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1953. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 1,290,080 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-270 d scores 0.52, ranking #234 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-270
TOI-270
- Surface temperature
- 3,506 K (Sun: 5,772 K)
- Mass
- 0.39 M☉
- Radius
- 0.38 R☉
The TOI-270 Planetary System
TOI-270 d is one of 3 known planets in the TOI-270 system. Its siblings:
TOI-270 d — Complete Data
| Radius | 2.000 Earth radii (0.178 Jupiter radii) |
|---|---|
| Mass | 4.20 Earth masses (0.013 Jupiter masses) |
| Density | 2.90 g/cm³ (Earth: 5.51) |
| Orbital period | 11.38 days |
| Eccentricity | 0.007 |
| Equilibrium temperature | 383 K (110 °C) |
| Earth Similarity Index | 0.52 |
| Distance from Earth | 73.3 light-years (22.5 parsecs) |
| Constellation | Pictor |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2019 |
Data: NASA Exoplanet Archive, last updated 2025-10-09. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-270 d
Is TOI-270 d habitable?
TOI-270 d is not known to orbit within the habitable zone of TOI-270, and as a mini-Neptune it is an unlikely candidate for life as we know it.
How far away is TOI-270 d?
TOI-270 d is about 73 light-years from Earth in the constellation Pictor. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 1,290,080 years to get there.
How big is TOI-270 d compared to Earth?
TOI-270 d has 2.00 times the radius of Earth and about 4.2 times its mass.
How long is a year on TOI-270 d?
One orbit around TOI-270 takes 11.4 Earth days — short enough that 32 of its years would fit into one Earth year.
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