Kepler-186b

Kepler-186b (also known as KOI-571.03) is an exoplanet located around 582 light-years away from Earth. Kepler-186b is orbiting a red dwarf known as Kepler-186, named after the space telescope that found it.

Kepler-186b is the innermost planet and the smallest of its system, and thus not suitable for life. The orbital period of this planet is just under four Earth days long due to its location near the parent star.

It is tidally locked. As a result, one hemisphere is in eternal daylight while the other hemisphere is in endless darkness. The other planets in the system are Kepler-186c, d, e, and f, of which only Kepler-186f is within the habitable zone.