TOI-1259 A b
TOI-1259 A b is a hot Jupiter orbiting TOI-1259 A in the constellation Draco. It lies about 385 light-years from Earth and was discovered in 2021 using the transit method.
How Big Is TOI-1259 A b?
TOI-1259 A b has a radius of 11.60 times that of Earth, or 1.03 times the radius of Jupiter. Its mass is 141 times that of Earth, giving it a density of 0.49 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is TOI-1259 A b in the Habitable Zone?
The position of TOI-1259 A b relative to the habitable zone of TOI-1259 A cannot be precisely determined from the available orbital data.
Orbit and Year Length
A year on TOI-1259 A b — one full orbit around TOI-1259 A — lasts 3.48 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.041 AU — closer to its star than Mercury is to the Sun.
How Was TOI-1259 A b Discovered?
TOI-1259 A b was discovered in 2021 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-1259 A b?
TOI-1259 A b is 385.2 light-years (118.1 parsecs) from Earth. Light arriving here tonight left the planet around the year 1641. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 6,779,520 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-1259 A b scores 0.08, ranking #4,598 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: TOI-1259 A
TOI-1259 A b belongs to a system of 2 stars; it orbits TOI-1259 A.
TOI-1259 A
- Mass
- 0.75 M☉
- Radius
- 0.72 R☉
Planetary System
TOI-1259 A b is the only planet known to orbit TOI-1259 A so far.
TOI-1259 A b — Complete Data
| Radius | 11.600 Earth radii (1.035 Jupiter radii) |
|---|---|
| Mass | 141.00 Earth masses (0.444 Jupiter masses) |
| Density | 0.49 g/cm³ (Earth: 5.51) |
| Orbital period | 3.48 days |
| Orbital distance | 0.041 AU |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 385.2 light-years (118.1 parsecs) |
| Constellation | Draco |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2021 |
Data: NASA Exoplanet Archive, last updated 2026-06-04. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About TOI-1259 A b
Is TOI-1259 A b habitable?
TOI-1259 A b is not known to orbit within the habitable zone of TOI-1259 A, and as a hot Jupiter it is an unlikely candidate for life as we know it.
How far away is TOI-1259 A b?
TOI-1259 A b is about 385 light-years from Earth in the constellation Draco. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 6,779,520 years to get there.
How big is TOI-1259 A b compared to Earth?
TOI-1259 A b has 11.60 times the radius of Earth and about 141 times its mass.
How long is a year on TOI-1259 A b?
One orbit around TOI-1259 A takes 3.5 Earth days — short enough that 105 of its years would fit into one Earth year.
Explore TOI-1259 A b in the app
Browse, filter and compare 6,000+ exoplanets on iPhone, iPad and Apple Watch — with habitable-zone views, widgets and offline data.
