TOI-1899 b
TOI-1899 b is a cold gas giant orbiting TOI-1899 in the constellation Cygnus. It lies about 419 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is TOI-1899 b?
TOI-1899 b has a radius of 11.10 times that of Earth, or 0.99 times the radius of Jupiter. Its mass is 213 times that of Earth, giving it a density of 0.85 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-1899 b in the Habitable Zone?
TOI-1899 b orbits inside the inner edge of the habitable zone of TOI-1899. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-1899: 0.228–0.578 AU (conservative: 0.288–0.548 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-1899 b
The equilibrium temperature of TOI-1899 b is about 378 K (105 °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. It receives 3.40 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-1899 b — one full orbit around TOI-1899 — lasts 29.1 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.153 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.044).
How Was TOI-1899 b Discovered?
TOI-1899 b was discovered in 2020 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-1899 b?
TOI-1899 b is 418.9 light-years (128.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1608. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 7,372,640 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-1899 b scores 0.28, ranking #2,317 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-1899
TOI-1899
- Surface temperature
- 3,926 K (Sun: 5,772 K)
- Mass
- 0.63 M☉
- Radius
- 0.61 R☉
- Age
- 7.1 billion years (Sun: 4.6)
Planetary System
TOI-1899 b is the only planet known to orbit TOI-1899 so far.
TOI-1899 b — Complete Data
| Radius | 11.097 Earth radii (0.990 Jupiter radii) |
|---|---|
| Mass | 212.95 Earth masses (0.670 Jupiter masses) |
| Density | 0.85 g/cm³ (Earth: 5.51) |
| Orbital period | 29.09 days |
| Orbital distance | 0.153 AU |
| Eccentricity | 0.044 |
| Equilibrium temperature | 378 K (105 °C) |
| Stellar irradiation | 3.40× Earth |
| Earth Similarity Index | 0.28 |
| Distance from Earth | 418.9 light-years (128.4 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2024-04-15. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-1899 b
Is TOI-1899 b habitable?
No — TOI-1899 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-1899 b?
TOI-1899 b is about 419 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 7,372,640 years to get there.
How big is TOI-1899 b compared to Earth?
TOI-1899 b has 11.10 times the radius of Earth and about 213 times its mass.
How long is a year on TOI-1899 b?
One orbit around TOI-1899 takes 29.1 Earth days — short enough that 13 of its years would fit into one Earth year.
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