K2-138 b

A confirmed exoplanet orbiting K2-138.

Compared with Earth

Size
About 1.5 times Earth's width.
Mass
About 3.1 times Earth's mass.
Year
A year here lasts about 2.4 Earth days.

Planet

Radius
1.51 × Earth
Mass
3.1 × Earth
Density
4.9 g/cm³
Equilibrium temperature
Unknown
Starlight received
Unknown
Orbital period
2.353 days
Average distance from its star
0.03385 AU

Star

Host star
K2-138
Spectral class
G — sun-like
Surface temperature
5,356 K
Radius
0.863 × Sun
Mass
0.935 × Sun
Age
2.8 billion years

System

Distance from Earth
660.7 light-years (202.6 parsecs)
Stars in system
1
Known planets
6

Discovery

Year
2017
Method
Transit
Facility
K2

Data from the NASA Exoplanet Archive, synced October 14, 2026.