About this world
Kepler-1521 b is a sub-Neptune orbiting Kepler-1521, an orange dwarf 675 light-years from Earth. It is about 2.5 times the size of Earth. It completes an orbit every 47.1 days at 0.23 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 391 K (118 °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 2016 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction.