stars
exoplanets
news
Exoplanet K2 138 b
Exoplanet K2 138 b orbits star K2 138 that lies 660 light years away from the Sun.
It weighs about 3.1 Earth masses and orbits its star much closer than Earth orbits Sun.
Sun distance
660 light years
660 light years
Loading may take a moment.
K2 138 b
Exoplanet, super-earth
Star: K2 138
Distance from the star: 0.03385 AU
Orbit around star: 2.35309 days
+
Orbital period
Orbital period of exoplanet K2 138 b around its star is 2.35309 days.
The orbital period of an exoplanet is the time it takes to complete one full orbit around its star, usually measured in days. Most of the exoplanets discovered so far have orbital periods of less than one year...
More about Orbital period in StellarGuide
Eccentricity: 0.048Basic characteristic
Mass: 3.1 M Earth
Exoplanet mass
Exoplanet K2 138 b has 3.1 Earth masses, or 0.21 times the mass of Uranus.
The mass of an exoplanet is one of the most important characteristics for understanding what kind of world it is — whether it’s small and rocky like Earth or large and gaseous like Jupiter. Mass provides key information about the planet’s composition, gravity, and formation history...
More about Exoplanet mass in StellarGuide
Size: 1.51 R Earth | 0.1 R Jupiter
Density: 4964 kg/m3 | 90.04 % EarthAdvertisement
K2 138 system structure
Exoplanet K2 138 b orbits star K2 138, which has lower mass than Sun. It is one of 6 known exoplanets orbiting this star.
|
|
K2 138 | ||||||||
| K2 138 b | 0.03 AU | 3.1 M⊕ | 1.5 R⊕ | 2.4 days | |||||
| K2 138 c | 0.04 AU | 6.3 M⊕ | 2.3 R⊕ | 3.6 days | |||||
| K2 138 d | 0.06 AU | 7.9 M⊕ | 2.4 R⊕ | 5.4 days | |||||
| K2 138 e | 0.08 AU | 13 M⊕ | 3.4 R⊕ | 8.3 days | |||||
| K2 138 f | 0.1 AU | 8.7 M⊕ | 2.9 R⊕ | 12.8 days | |||||
| K2 138 g | 0.23 AU | 25.5 M⊕ | 3 R⊕ | 42 days | |||||
Comparison
When comparing to the Solar system planets, K2 138 b has 21 % of mass of Uranus and it orbits its star closer than Mercury orbits the Sun.
| Mercury | Venus | Earth | Mars | Jupiter | Saturn | Uranus | Neptune | ||
|---|---|---|---|---|---|---|---|---|---|
|
Mass | 56.36 | 3.8 | 3.1 | 28.18 | 0.01 | 0.03 | 0.21 | 0.18 |
|
Size | 3.94 | 1.59 | 1.51 | 2.85 | 0.13 | 0.17 | 0.38 | 0.4 |
|
Density | 0.92 | 0.95 | 0.9 | 1.22 | 3.99 | 7.13 | 3.95 | 2.87 |
|
Distance | 0.09 | 0.05 | 0.03 | 0.02 | 0.01 | 0 | 0 | 0 |