TOI-277 b
TOI-277 b is a mini-Neptune orbiting TOI-277 in the constellation Cetus. It lies about 211 light-years from Earth and was discovered in 2022 using the transit method.
How Big Is TOI-277 b?
TOI-277 b has a radius of 2.65 times that of Earth.
Is TOI-277 b in the Habitable Zone?
TOI-277 b orbits inside the inner edge of the habitable zone of TOI-277. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-277: 0.143–0.361 AU (conservative: 0.181–0.342 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
See the full interactive habitable-zone view in the Exoplanet Explorer app ›
Orbit and Year Length
A year on TOI-277 b — one full orbit around TOI-277 — lasts 3.99 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.027 AU — closer to its star than Mercury is to the Sun.
How Was TOI-277 b Discovered?
TOI-277 b was discovered in 2022 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-277 b?
TOI-277 b is 210.9 light-years (64.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1816. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 3,711,840 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-277 b scores 0.24, ranking #3,222 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-277
TOI-277
- Surface temperature
- 4,031 K (Sun: 5,772 K)
- Mass
- 0.16 M☉
- Radius
- 0.36 R☉
Planetary System
TOI-277 b is the only planet known to orbit TOI-277 so far.
TOI-277 b — Complete Data
| Radius | 2.650 Earth radii (0.236 Jupiter radii) |
|---|---|
| Orbital period | 3.99 days |
| Orbital distance | 0.027 AU |
| Earth Similarity Index | 0.24 |
| Distance from Earth | 210.9 light-years (64.7 parsecs) |
| Constellation | Cetus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2022 |
Data: NASA Exoplanet Archive, last updated 2022-11-29. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-277 b
Is TOI-277 b habitable?
No — TOI-277 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-277 b?
TOI-277 b is about 211 light-years from Earth in the constellation Cetus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 3,711,840 years to get there.
How big is TOI-277 b compared to Earth?
TOI-277 b has 2.65 times the radius of Earth.
How long is a year on TOI-277 b?
One orbit around TOI-277 takes 4.0 Earth days — short enough that 91 of its years would fit into one Earth year.
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