About this world
KOI-3503 b is an Earth-sized planet orbiting KOI-3503, a yellow-white F-type star 2.89 thousand light-years from Earth. It is about 1.2 times the size of Earth and holds 9.2 Earth masses. It completes an orbit every 21.2 days at 0.14 AU from its star, closer than Mercury is to the Sun.
Its equilibrium temperature is about 785 K (512 °C): far too hot for liquid water on its surface. By the "cosmic shoreline", it has likely held on to an atmosphere.
It was discovered in 2021 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction. KOI-3503 has 2 known planets; the others are KOI-3503 c.