High Quality Content by WIKIPEDIA articles! Alpha Centauri Bb is an extrasolar planet orbiting the K-type main-sequence star Alpha Centauri B, located 4.37 light-years from Earth in the southern constellation of Centaurus. It is the closest extrasolar planet to Earth discovered, and the lowest-minimum-mass planet detected so far around a solar-type star. The announcement of its existence in October 2012 received widespread media attention, and its discovery is seen as an important landmark in exoplanet research.