TOI-1859 b
TOI-1859 b is a cold gas giant orbiting TOI-1859 in the constellation Draco. It lies about 732 light-years from Earth and was discovered in 2023 using the transit method.
How Big Is TOI-1859 b?
TOI-1859 b has a radius of 9.75 times that of Earth, or 0.87 times the radius of Jupiter.
Is TOI-1859 b in the Habitable Zone?
TOI-1859 b orbits inside the inner edge of the habitable zone of TOI-1859. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-1859: 1.188–2.765 AU (conservative: 1.505–2.621 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-1859 b — one full orbit around TOI-1859 — lasts 63.5 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.337 AU — closer to its star than Mercury is to the Sun. Its orbit is highly elliptical (eccentricity 0.57), swinging dramatically closer to and farther from its star.
How Was TOI-1859 b Discovered?
TOI-1859 b was discovered in 2023 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-1859 b?
TOI-1859 b is 731.8 light-years (224.4 parsecs) from Earth. Light arriving here tonight left the planet around the year 1295. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 12,879,680 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-1859 b scores 0.12, ranking #4,325 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-1859
TOI-1859
- Surface temperature
- 6,341 K (Sun: 5,772 K)
- Mass
- 1.29 M☉
- Radius
- 1.36 R☉
- Age
- 1.4 billion years (Sun: 4.6)
Planetary System
TOI-1859 b is the only planet known to orbit TOI-1859 so far.
TOI-1859 b — Complete Data
| Radius | 9.752 Earth radii (0.870 Jupiter radii) |
|---|---|
| Orbital period | 63.48 days |
| Orbital distance | 0.337 AU |
| Eccentricity | 0.570 |
| Earth Similarity Index | 0.12 |
| Distance from Earth | 731.8 light-years (224.4 parsecs) |
| Constellation | Draco |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2023 |
Data: NASA Exoplanet Archive, last updated 2023-06-12. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-1859 b
Is TOI-1859 b habitable?
No — TOI-1859 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-1859 b?
TOI-1859 b is about 732 light-years from Earth in the constellation Draco. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 12,879,680 years to get there.
How big is TOI-1859 b compared to Earth?
TOI-1859 b has 9.75 times the radius of Earth.
How long is a year on TOI-1859 b?
One orbit around TOI-1859 takes 63.5 Earth days.
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