About this world
Kepler-603 b is a sub-Neptune orbiting Kepler-603, a yellow, Sun-like star 5.02 thousand light-years from Earth. It is about 2.6 times the size of Earth. It completes an orbit every 21.1 days at 0.16 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 731 K (458 °C): far too hot for liquid water on its surface. At its size it almost certainly keeps a deep envelope of hydrogen and helium.
It was discovered in 2016 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction. Kepler-603 has 3 known planets; the others are Kepler-603 d and Kepler-603 c.