TOI-157 b
TOI-157 b is a hot Jupiter orbiting the G9 IV star TOI-157 in the constellation Mensa. It lies about 1,160 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is TOI-157 b?
TOI-157 b has a radius of 14.41 times that of Earth, or 1.29 times the radius of Jupiter. Its mass is 375 times that of Earth, giving it a density of 0.69 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-157 b in the Habitable Zone?
TOI-157 b orbits inside the inner edge of the habitable zone of TOI-157. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-157: 0.785–1.870 AU (conservative: 0.994–1.773 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-157 b
The equilibrium temperature of TOI-157 b is about 1,588 K (1,315 °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. It receives 1,062 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-157 b — one full orbit around TOI-157 — lasts 2.08 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.031 AU — closer to its star than Mercury is to the Sun.
How Was TOI-157 b Discovered?
TOI-157 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-157 b?
TOI-157 b is 1,160.1 light-years (355.7 parsecs) from Earth. Light arriving here tonight left the planet about 1,160 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 20,417,760 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-157 b scores 0.06, ranking #5,083 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-157
TOI-157
- Spectral type
- G9 IV
- Surface temperature
- 5,404 K (Sun: 5,772 K)
- Mass
- 0.95 M☉
- Radius
- 1.17 R☉
- Luminosity
- 1.0470 L☉
- Age
- 12.8 billion years (Sun: 4.6)
Planetary System
TOI-157 b is the only planet known to orbit TOI-157 so far.
TOI-157 b — Complete Data
| Radius | 14.415 Earth radii (1.286 Jupiter radii) |
|---|---|
| Mass | 375.04 Earth masses (1.180 Jupiter masses) |
| Density | 0.69 g/cm³ (Earth: 5.51) |
| Orbital period | 2.08 days |
| Orbital distance | 0.031 AU |
| Equilibrium temperature | 1,588 K (1,315 °C) |
| Stellar irradiation | 1,062.00× Earth |
| Earth Similarity Index | 0.06 |
| Distance from Earth | 1,160.1 light-years (355.7 parsecs) |
| Constellation | Mensa |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2020-07-17. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-157 b
Is TOI-157 b habitable?
No — TOI-157 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-157 b?
TOI-157 b is about 1,160 light-years from Earth in the constellation Mensa. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 20,417,760 years to get there.
How big is TOI-157 b compared to Earth?
TOI-157 b has 14.41 times the radius of Earth and about 375 times its mass.
How long is a year on TOI-157 b?
One orbit around TOI-157 takes 2.1 Earth days — short enough that 175 of its years would fit into one Earth year.
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