XO-1 b
XO-1 b is a hot Jupiter orbiting XO-1 in the constellation Corona Borealis. It lies about 533 light-years from Earth and was discovered in 2006 using the transit method.
How Big Is XO-1 b?
XO-1 b has a radius of 12.78 times that of Earth, or 1.14 times the radius of Jupiter. Its mass is 264 times that of Earth.
Is XO-1 b in the Habitable Zone?
The position of XO-1 b relative to the habitable zone of XO-1 cannot be precisely determined from the available orbital data.
Habitable zone of XO-1: 0.655–1.545 AU (conservative: 0.830–1.464 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 XO-1 b — one full orbit around XO-1 — lasts 3.94 Earth days, shorter than Mercury's 88-day year.
How Was XO-1 b Discovered?
XO-1 b was discovered in 2006 using the transit method, with observations from XO.
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 XO-1 b?
XO-1 b is 533.4 light-years (163.6 parsecs) from Earth. Light arriving here tonight left the planet around the year 1493. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 9,387,840 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. XO-1 b scores 0.07, ranking #4,863 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: XO-1
XO-1
- Surface temperature
- 5,750 K (Sun: 5,772 K)
- Mass
- 0.88 M☉
- Radius
- 0.88 R☉
Planetary System
XO-1 b is the only planet known to orbit XO-1 so far.
XO-1 b — Complete Data
| Radius | 12.778 Earth radii (1.140 Jupiter radii) |
|---|---|
| Mass | 263.80 Earth masses (0.830 Jupiter masses) |
| Orbital period | 3.94 days |
| Earth Similarity Index | 0.07 |
| Distance from Earth | 533.4 light-years (163.6 parsecs) |
| Constellation | Corona Borealis |
| Discovery method | Transit |
| Discovery facility | XO |
| Discovery year | 2006 |
Data: NASA Exoplanet Archive, last updated 2018-04-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About XO-1 b
Is XO-1 b habitable?
XO-1 b is not known to orbit within the habitable zone of XO-1, and as a hot Jupiter it is an unlikely candidate for life as we know it.
How far away is XO-1 b?
XO-1 b is about 533 light-years from Earth in the constellation Corona Borealis. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 9,387,840 years to get there.
How big is XO-1 b compared to Earth?
XO-1 b has 12.78 times the radius of Earth and about 264 times its mass.
How long is a year on XO-1 b?
One orbit around XO-1 takes 3.9 Earth days — short enough that 93 of its years would fit into one Earth year.
Explore XO-1 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.
