TOI-1855 b
TOI-1855 b is a hot Jupiter orbiting TOI-1855 in the constellation Boötes. It lies about 577 light-years from Earth and was discovered in 2024 using the transit method.
How Big Is TOI-1855 b?
TOI-1855 b has a radius of 18.49 times that of Earth, or 1.65 times the radius of Jupiter. Its mass is 360 times that of Earth, giving it a density of 0.31 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-1855 b in the Habitable Zone?
TOI-1855 b orbits inside the inner edge of the habitable zone of TOI-1855. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of TOI-1855: 0.689–1.645 AU (conservative: 0.873–1.560 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on TOI-1855 b
The equilibrium temperature of TOI-1855 b is about 1,701 K (1,428 °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.
Orbit and Year Length
A year on TOI-1855 b — one full orbit around TOI-1855 — lasts just 32.7 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.024 AU — closer to its star than Mercury is to the Sun. Its orbit is nearly circular (eccentricity 0.033).
How Was TOI-1855 b Discovered?
TOI-1855 b was discovered in 2024 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-1855 b?
TOI-1855 b is 576.8 light-years (176.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1450. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 10,151,680 years to make the journey.
The Host Star: TOI-1855
TOI-1855
- Surface temperature
- 5,359 K (Sun: 5,772 K)
- Mass
- 0.99 M☉
- Radius
- 1.04 R☉
- Luminosity
- 0.8040 L☉
- Age
- 8.2 billion years (Sun: 4.6)
Planetary System
TOI-1855 b is the only planet known to orbit TOI-1855 so far.
TOI-1855 b — Complete Data
| Radius | 18.495 Earth radii (1.650 Jupiter radii) |
|---|---|
| Mass | 360.10 Earth masses (1.133 Jupiter masses) |
| Density | 0.31 g/cm³ (Earth: 5.51) |
| Orbital period | 1.36 days |
| Orbital distance | 0.024 AU |
| Eccentricity | 0.033 |
| Equilibrium temperature | 1,701 K (1,428 °C) |
| Distance from Earth | 576.8 light-years (176.8 parsecs) |
| Constellation | Boötes |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2024 |
Data: NASA Exoplanet Archive, last updated 2024-07-23. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-1855 b
Is TOI-1855 b habitable?
No — TOI-1855 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is TOI-1855 b?
TOI-1855 b is about 577 light-years from Earth in the constellation Boötes. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 10,151,680 years to get there.
How big is TOI-1855 b compared to Earth?
TOI-1855 b has 18.49 times the radius of Earth and about 360 times its mass.
How long is a year on TOI-1855 b?
One orbit around TOI-1855 takes 1.4 Earth days — short enough that 268 of its years would fit into one Earth year.
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