KPS-1 b
KPS-1 b is a hot Jupiter orbiting the K1 V star KPS-1 in the constellation Ursa Major. It lies about 857 light-years from Earth and was discovered in 2018 using the transit method.
How Big Is KPS-1 b?
KPS-1 b has a radius of 11.55 times that of Earth, or 1.03 times the radius of Jupiter. Its mass is 346 times that of Earth, giving it a density of 1.31 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is KPS-1 b in the Habitable Zone?
KPS-1 b orbits inside the inner edge of the habitable zone of KPS-1. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of KPS-1: 0.563–1.353 AU (conservative: 0.713–1.282 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on KPS-1 b
The equilibrium temperature of KPS-1 b is about 1,459 K (1,186 °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. It receives 729 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on KPS-1 b — one full orbit around KPS-1 — lasts just 41.0 hours, shorter than Mercury's 88-day year. It orbits at an average distance of 0.027 AU — closer to its star than Mercury is to the Sun.
How Was KPS-1 b Discovered?
KPS-1 b was discovered in 2018 using the transit method, with observations from Acton Sky Portal Observatory.
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 KPS-1 b?
KPS-1 b is 856.8 light-years (262.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1170. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 15,079,680 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. KPS-1 b scores 0.08, ranking #4,708 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: KPS-1
KPS-1
- Spectral type
- K1 V
- Surface temperature
- 5,165 K (Sun: 5,772 K)
- Mass
- 0.89 M☉
- Radius
- 0.91 R☉
Planetary System
KPS-1 b is the only planet known to orbit KPS-1 so far.
KPS-1 b — Complete Data
| Radius | 11.545 Earth radii (1.030 Jupiter radii) |
|---|---|
| Mass | 346.43 Earth masses (1.090 Jupiter masses) |
| Density | 1.31 g/cm³ (Earth: 5.51) |
| Orbital period | 1.71 days |
| Orbital distance | 0.027 AU |
| Equilibrium temperature | 1,459 K (1,186 °C) |
| Stellar irradiation | 729.00× Earth |
| Earth Similarity Index | 0.08 |
| Distance from Earth | 856.8 light-years (262.7 parsecs) |
| Constellation | Ursa Major |
| Discovery method | Transit |
| Discovery facility | Acton Sky Portal Observatory |
| Discovery year | 2018 |
Data: NASA Exoplanet Archive, last updated 2018-04-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About KPS-1 b
Is KPS-1 b habitable?
No — KPS-1 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is KPS-1 b?
KPS-1 b is about 857 light-years from Earth in the constellation Ursa Major. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 15,079,680 years to get there.
How big is KPS-1 b compared to Earth?
KPS-1 b has 11.55 times the radius of Earth and about 346 times its mass.
How long is a year on KPS-1 b?
One orbit around KPS-1 takes 1.7 Earth days — short enough that 214 of its years would fit into one Earth year.
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