TOI-5699 b
TOI-5699 b is a cold gas giant orbiting TOI-5699 in the constellation Hercules. It lies about 994 light-years from Earth and was discovered in 2026 using the transit method.
How Big Is TOI-5699 b?
TOI-5699 b has a radius of 11.16 times that of Earth, or 1.00 times the radius of Jupiter. Its mass is 79.5 times that of Earth.
Is TOI-5699 b in the Habitable Zone?
TOI-5699 b orbits inside the inner edge of the habitable zone of TOI-5699. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-5699: 1.276–2.996 AU (conservative: 1.616–2.840 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-5699 b
The equilibrium temperature of TOI-5699 b is about 906 K (633 °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 112 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on TOI-5699 b — one full orbit around TOI-5699 — lasts 22.0 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.160 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.30), swinging dramatically closer to and farther from its star.
How Was TOI-5699 b Discovered?
TOI-5699 b was discovered in 2026 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-5699 b?
TOI-5699 b is 993.9 light-years (304.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1033. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 17,492,640 years to make the journey.
The Host Star: TOI-5699
TOI-5699
- Surface temperature
- 5,905 K (Sun: 5,772 K)
- Mass
- 1.13 M☉
- Radius
- 1.64 R☉
- Age
- 6.6 billion years (Sun: 4.6)
Planetary System
TOI-5699 b is the only planet known to orbit TOI-5699 so far.
TOI-5699 b — Complete Data
| Radius | 11.164 Earth radii (0.996 Jupiter radii) |
|---|---|
| Mass | 79.46 Earth masses (0.250 Jupiter masses) |
| Orbital period | 22.02 days |
| Orbital distance | 0.160 AU |
| Eccentricity | 0.300 |
| Equilibrium temperature | 906 K (633 °C) |
| Stellar irradiation | 112.00× Earth |
| Distance from Earth | 993.9 light-years (304.7 parsecs) |
| Constellation | Hercules |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2026 |
Data: NASA Exoplanet Archive, last updated 2026-10-15. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-5699 b
Is TOI-5699 b habitable?
No — TOI-5699 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-5699 b?
TOI-5699 b is about 994 light-years from Earth in the constellation Hercules. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 17,492,640 years to get there.
How big is TOI-5699 b compared to Earth?
TOI-5699 b has 11.16 times the radius of Earth and about 79.5 times its mass.
How long is a year on TOI-5699 b?
One orbit around TOI-5699 takes 22.0 Earth days — short enough that 17 of its years would fit into one Earth year.
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