KELT-12 b
KELT-12 b is a hot Jupiter orbiting KELT-12 in the constellation Hercules. It lies about 1,200 light-years from Earth and was discovered in 2017 using the transit method.
How Big Is KELT-12 b?
KELT-12 b has a radius of 19.95 times that of Earth, or 1.78 times the radius of Jupiter. Its mass is 302 times that of Earth, giving it a density of 0.21 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is KELT-12 b in the Habitable Zone?
KELT-12 b orbits inside the inner edge of the habitable zone of KELT-12. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of KELT-12: 2.033–4.737 AU (conservative: 2.575–4.491 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on KELT-12 b
The equilibrium temperature of KELT-12 b is about 1,800 K (1,527 °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 1,749 times the stellar energy that Earth gets from the Sun.
Orbit and Year Length
A year on KELT-12 b — one full orbit around KELT-12 — lasts 5.03 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.067 AU — closer to its star than Mercury is to the Sun.
How Was KELT-12 b Discovered?
KELT-12 b was discovered in 2017 using the transit method, with observations from KELT-North.
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 KELT-12 b?
KELT-12 b is 1,200.4 light-years (368.0 parsecs) from Earth. Light arriving here tonight left the planet about 1,200 years ago. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 21,127,040 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. KELT-12 b scores 0.05, ranking #5,302 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: KELT-12
KELT-12
- Surface temperature
- 6,279 K (Sun: 5,772 K)
- Mass
- 1.59 M☉
- Radius
- 2.37 R☉
- Luminosity
- 7.7999 L☉
- Age
- 2.2 billion years (Sun: 4.6)
Planetary System
KELT-12 b is the only planet known to orbit KELT-12 so far.
KELT-12 b — Complete Data
| Radius | 19.952 Earth radii (1.780 Jupiter radii) |
|---|---|
| Mass | 301.94 Earth masses (0.950 Jupiter masses) |
| Density | 0.21 g/cm³ (Earth: 5.51) |
| Orbital period | 5.03 days |
| Orbital distance | 0.067 AU |
| Equilibrium temperature | 1,800 K (1,527 °C) |
| Stellar irradiation | 1,749.00× Earth |
| Earth Similarity Index | 0.05 |
| Distance from Earth | 1,200.4 light-years (368.0 parsecs) |
| Constellation | Hercules |
| Discovery method | Transit |
| Discovery facility | KELT-North |
| Discovery year | 2017 |
Data: NASA Exoplanet Archive, last updated 2017-04-24. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About KELT-12 b
Is KELT-12 b habitable?
No — KELT-12 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is KELT-12 b?
KELT-12 b is about 1,200 light-years from Earth in the constellation Hercules. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 21,127,040 years to get there.
How big is KELT-12 b compared to Earth?
KELT-12 b has 19.95 times the radius of Earth and about 302 times its mass.
How long is a year on KELT-12 b?
One orbit around KELT-12 takes 5.0 Earth days — short enough that 73 of its years would fit into one Earth year.
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