K2-39 b
K2-39 b is a hot Jupiter orbiting K2-39 in the constellation Aquarius. It lies about 1,003 light-years from Earth and was discovered in 2016 using the transit method.
How Big Is K2-39 b?
K2-39 b has a radius of 6.28 times that of Earth, or 0.56 times the radius of Jupiter. Its mass is 28.6 times that of Earth.
Is K2-39 b in the Habitable Zone?
The position of K2-39 b relative to the habitable zone of K2-39 cannot be precisely determined from the available orbital data.
Habitable zone of K2-39: 1.669–4.055 AU (conservative: 2.114–3.845 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 K2-39 b — one full orbit around K2-39 — lasts 4.61 Earth days, shorter than Mercury's 88-day year.
How Was K2-39 b Discovered?
K2-39 b was discovered in 2016 using the transit method, with observations from K2.
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 K2-39 b?
K2-39 b is 1,002.8 light-years (307.5 parsecs) from Earth. Light arriving here tonight left the planet around the year 1024. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 17,649,280 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. K2-39 b scores 0.13, ranking #4,302 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: K2-39
K2-39
- Surface temperature
- 4,881 K (Sun: 5,772 K)
- Mass
- 0.66 M☉
- Radius
- 2.97 R☉
Planetary System
K2-39 b is the only planet known to orbit K2-39 so far.
K2-39 b — Complete Data
| Radius | 6.277 Earth radii (0.560 Jupiter radii) |
|---|---|
| Mass | 28.60 Earth masses (0.090 Jupiter masses) |
| Orbital period | 4.61 days |
| Earth Similarity Index | 0.13 |
| Distance from Earth | 1,002.8 light-years (307.5 parsecs) |
| Constellation | Aquarius |
| Discovery method | Transit |
| Discovery facility | K2 |
| Discovery year | 2016 |
Data: NASA Exoplanet Archive, last updated 2018-04-25. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About K2-39 b
Is K2-39 b habitable?
K2-39 b is not known to orbit within the habitable zone of K2-39, and as a hot Jupiter it is an unlikely candidate for life as we know it.
How far away is K2-39 b?
K2-39 b is about 1,003 light-years from Earth in the constellation Aquarius. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 17,649,280 years to get there.
How big is K2-39 b compared to Earth?
K2-39 b has 6.28 times the radius of Earth and about 28.6 times its mass.
How long is a year on K2-39 b?
One orbit around K2-39 takes 4.6 Earth days — short enough that 79 of its years would fit into one Earth year.
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