A hand out image made available by the European Southern Observatory on August 24 2016, shows an artist's impression of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. The double star Alpha Centauri AB also appears in the image between the planet and Proxima itself. Proxima b is a little more massive than the Earth and orbits in the habitable zone around Proxima Centauri, where the temperature is suitable for liquid water to exist on its surface. Scientists on August 24, 2016 announced the discovery of an Earth-sized planet orbiting the star nearest our Sun, opening up the glittering prospect of a habitable world that may one day be explored by robots. Named Proxima b, the planet is in a "temperate" zone compatible with the presence of liquid water -- a key ingredient for life. / AFP / EUROPEAN SOUTHERN OBSERVATORY / M. Kornmesser (Photo credit should read M. KORNMESSER/AFP/Getty Images)