About this world
Kepler-397 c is a Neptune-like planet orbiting Kepler-397, a yellow, Sun-like star 3.16 thousand light-years from Earth. It is about 0.55 times the size of Jupiter. It completes an orbit every 135 days at 0.48 AU from its star.
Its equilibrium temperature is about 295 K (22 °C): too cold for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2014 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction. Kepler-397 has 2 known planets; the others are Kepler-397 b.