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Exoplanet K2-21 c
Exoplanet K2-21 c orbits star K2-21 that lies 273 light years away from the Sun.
It weighs about 3.88 Earth masses and orbits its star closer than Earth orbits Sun.
Sun distance
273 light years
273 light years
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K2-21 c
Exoplanet, sub-neptune
Star: K2-21
Distance from the star: 0.1026 AU
Orbit around star: 15.49955 days
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Orbital period
Orbital period of exoplanet K2-21 c around its star is 15.49955 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
Basic characteristic
Mass: 3.88 M Earth
Exoplanet mass
Exoplanet K2-21 c has 3.88 Earth masses, or 0.27 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: 2.25 R Earth | 0.2 R Jupiter
Density: 1878 kg/m3 | 34.06 % Earth
Temperature: 420 K | 146.85 °C
Year of discovery: 2015 (transit)
Other designations of this exoplanet
EPIC 206011691 c
EPIC 206011691 c
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Comparison
When comparing to the Solar system planets, K2-21 c has 27 % of mass of Uranus and it orbits its star closer than Mercury orbits the Sun.
| Mercury | Venus | Earth | Mars | Jupiter | Saturn | Uranus | Neptune | ||
|---|---|---|---|---|---|---|---|---|---|
|
Mass | 70.55 | 4.76 | 3.88 | 35.27 | 0.01 | 0.04 | 0.27 | 0.23 |
|
Size | 5.88 | 2.37 | 2.25 | 4.25 | 0.2 | 0.25 | 0.56 | 0.59 |
|
Density | 0.35 | 0.36 | 0.34 | 0.46 | 1.51 | 2.7 | 1.49 | 1.09 |
|
Distance | 0.26 | 0.14 | 0.1 | 0.07 | 0.02 | 0.01 | 0.01 | 0 |
|
Temperature | 0.95 | 0.57 | 1.46 | 2.02 | 2.58 | 3.16 | 5.38 | 5.83 |
Habitability
Habitable zone of the star: 101.3 - 145.9 AU
The planet is too hot to sustain liquid water.
The planet is bigger than Earth and smaller than Neptune. Its average density 1878 kg/m3 points to a hot gas planet.