TOI-220 b
TOI-220 b is a sub-Neptune orbiting the K0 V star TOI-220 in the constellation Pictor. It lies about 296 light-years from Earth and was discovered in 2021 using the transit method.
How Big Is TOI-220 b?
TOI-220 b has a radius of 3.03 times that of Earth. Its mass is 13.8 times that of Earth, giving it a density of 2.73 g/cm³ — between that of rocky and gaseous planets.
Is TOI-220 b in the Habitable Zone?
TOI-220 b orbits inside the inner edge of the habitable zone of TOI-220. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-220: 0.557–1.331 AU (conservative: 0.705–1.262 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-220 b
The equilibrium temperature of TOI-220 b is about 805 K (532 °C) — hot enough to melt many metals. 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-220 b — one full orbit around TOI-220 — lasts 10.7 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.089 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.032).
How Was TOI-220 b Discovered?
TOI-220 b was discovered in 2021 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-220 b?
TOI-220 b is 296.0 light-years (90.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1730. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 5,209,600 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-220 b scores 0.23, ranking #3,559 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-220
TOI-220
- Spectral type
- K0 V
- Surface temperature
- 5,298 K (Sun: 5,772 K)
- Mass
- 0.83 M☉
- Radius
- 0.86 R☉
- Age
- 10.1 billion years (Sun: 4.6)
Planetary System
TOI-220 b is the only planet known to orbit TOI-220 so far.
TOI-220 b — Complete Data
| Radius | 3.030 Earth radii (0.270 Jupiter radii) |
|---|---|
| Mass | 13.80 Earth masses (0.043 Jupiter masses) |
| Density | 2.73 g/cm³ (Earth: 5.51) |
| Orbital period | 10.70 days |
| Orbital distance | 0.089 AU |
| Eccentricity | 0.032 |
| Equilibrium temperature | 805 K (532 °C) |
| Earth Similarity Index | 0.23 |
| Distance from Earth | 296.0 light-years (90.7 parsecs) |
| Constellation | Pictor |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2021-05-28. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-220 b
Is TOI-220 b habitable?
No — TOI-220 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-220 b?
TOI-220 b is about 296 light-years from Earth in the constellation Pictor. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 5,209,600 years to get there.
How big is TOI-220 b compared to Earth?
TOI-220 b has 3.03 times the radius of Earth and about 13.8 times its mass.
How long is a year on TOI-220 b?
One orbit around TOI-220 takes 10.7 Earth days — short enough that 34 of its years would fit into one Earth year.
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