Gliese 876 d is an extrasolar planet approximately 15 light-years away in the constellation of Aquarius (the Water-bearer). The planet was the third planet discovered orbiting the red dwarf star Gliese 876. At the time of its discovery, the planet had the lowest mass of any known extrasolar planet apart from the pulsar planets orbiting PSR B1257+12. Due to this low mass, it can be categorized as a super-Earth.
Read more about Gliese 876 D: Discovery, Orbit and Mass, Physical Characteristics