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Kepler-138 e is a Rocky exoplanet (a small, dense world with a solid surface) with a mass of 0.4 Earth masses. With an equilibrium temperature of 292 K (19°C), it lies within the habitable zone where liquid water could potentially exist on its surface. The planet completes one orbit around its star every 38.2 Earth days. It was discovered in 2022 using the transit timing variations method. It orbits the star Kepler-138, located approximately 67 parsecs (218 light-years) from Earth.
2022
Discovered
0.4
Earth Masses
292
Temperature (K)
Discovery Information
Discovery MethodTransit Timing Variations
Discovery Year2,022
Discovery FacilityMultiple Observatories
Orbital Properties
Orbital Period38.23 days
Semi-Major Axis0.1803 AU
Eccentricity0.112
Inclination88.53 deg
Physical Properties
Mass (Jupiter)0.0014 MJ
Mass (Earth)0.43 M⊕
Eq. Temperature292 K
Insolation Flux1.73 S⊕
Planetary Extremes
Where Kepler-138 e sits on the spectrum of all known exoplanets.
Mass0.4 M⊕
FeatherweightColossus
Temperature292 K
FrozenInferno
Year Length38.2 days
LightningGlacial
Star Distance0.180 AU
ScorchedFrozen exile
Star System View
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Orbit Comparison
Earth: 365.25 days (1 AU)Kepler-138 e: 38.2 Earth days (0.180 AU)
Host Star: Kepler-138
Effective Temperature3,841 K
Mass0.535 M☉
Radius0.535 R☉
Size vs Sun1.87x smaller
Luminosity0.056 L☉
Luminosity vs Sun17.9x dimmer
Metallicity [Fe/H]-0.18
Distance (pc)66.8624 pc
Distance (ly)218.1 light-years
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