Qatar-9 b
Qatar-9 b is a hot Jupiter orbiting the K5 V star Qatar-9 in the constellation Ursa Major. It lies about 697 light-years from Earth and was discovered in 2019 using the transit method.
How Big Is Qatar-9 b?
Qatar-9 b has a radius of 11.31 times that of Earth, or 1.01 times the radius of Jupiter. Its mass is 378 times that of Earth, giving it a density of 1.43 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is Qatar-9 b in the Habitable Zone?
Qatar-9 b orbits inside the inner edge of the habitable zone of Qatar-9. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of Qatar-9: 0.313–0.780 AU (conservative: 0.396–0.739 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 ›
Temperature on Qatar-9 b
The equilibrium temperature of Qatar-9 b is about 1,134 K (861 °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 Qatar-9 b — one full orbit around Qatar-9 — lasts just 37.0 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.023 AU — closer to its star than Mercury is to the Sun.
How Was Qatar-9 b Discovered?
Qatar-9 b was discovered in 2019 using the transit method, with observations from Qatar.
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 Qatar-9 b?
Qatar-9 b is 697.2 light-years (213.8 parsecs) from Earth. Light arriving here tonight left the planet around the year 1329. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 12,270,720 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. Qatar-9 b scores 0.08, ranking #4,632 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: Qatar-9
Qatar-9
- Spectral type
- K5 V
- Surface temperature
- 4,309 K (Sun: 5,772 K)
- Mass
- 0.72 M☉
- Radius
- 0.70 R☉
- Luminosity
- 0.1510 L☉
- Age
- 7.5 billion years (Sun: 4.6)
Planetary System
Qatar-9 b is the only planet known to orbit Qatar-9 so far.
Qatar-9 b — Complete Data
| Radius | 11.310 Earth radii (1.009 Jupiter radii) |
|---|---|
| Mass | 378.22 Earth masses (1.190 Jupiter masses) |
| Density | 1.43 g/cm³ (Earth: 5.51) |
| Orbital period | 1.54 days |
| Orbital distance | 0.023 AU |
| Equilibrium temperature | 1,134 K (861 °C) |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 697.2 light-years (213.8 parsecs) |
| Constellation | Ursa Major |
| Discovery method | Transit |
| Discovery facility | Qatar |
| Discovery year | 2019 |
Data: NASA Exoplanet Archive, last updated 2019-04-30. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About Qatar-9 b
Is Qatar-9 b habitable?
No — Qatar-9 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is Qatar-9 b?
Qatar-9 b is about 697 light-years from Earth in the constellation Ursa Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 12,270,720 years to get there.
How big is Qatar-9 b compared to Earth?
Qatar-9 b has 11.31 times the radius of Earth and about 378 times its mass.
How long is a year on Qatar-9 b?
One orbit around Qatar-9 takes 1.5 Earth days — short enough that 237 of its years would fit into one Earth year.
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