PARIS: Scientists Wednesday 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. The findings, based on data collected over 16 years, were reported in the peer-reviewed journal Nature. “We have finally succeeded in showing that a small-mass planet, most likely rocky, is orbiting the star closest to our solar system,” said co-author Julien Morin, an astrophysicist at the University of Montpellier in southern France. “Proxima b would probably be the first exoplanet visited by a probe made by humans,” he told Agence France-Presse. An exoplanet is any planet outside our Solar System. Lead author Guillem Anglada-Escude, an astronomer at Queen Mary University London, described the find as the “experience of a lifetime”. Working with European Southern Observatory telescopes in the north Chilean desert, his team used the so-called Doppler method to detect Proxima b and describe its properties. The professional star-gazers spent 60 consecutive days earlier this year looking for signs of gravitational pull on its host star, Proxima Centauri. Regular shifts in the star’s light spectrum — repeating every 11.2 days — gave a tantalizing clue. They revealed that the star alternately moved towards and away from our Solar System at the pace of a leisurely stroll, about five kilometers (three miles) per hour.