An Earth-mass planet orbiting α Centauri B

Exoplanets down to the size of Earth have been found, but not in the habitable zone—that is, at a distance from the parent star at which water, if present, would be liquid. There are planets in the habitable zone of stars cooler than our Sun, but for reasons such as tidal locking and strong stellar activity, they are unlikely to harbour water–carbon life as we know it. The detection of a habitable Earth-mass planet orbiting a star similar to our Sun is extremely difficult, because such a signal is overwhelmed by stellar perturbations. Here we report the detection of an Earth-mass planet orbiting our neighbour star α Centauri B, a member of the closest stellar system to the Sun. The planet has an orbital period of 3.236 days and is about 0.04 astronomical units from the star (one astronomical unit is the Earth–Sun distance). The detection of an Earth-mass planet orbiting our neighbour star α Centauri B is reported; the planet has an orbital period of 3.236 days and is about 0.04 astronomical units from the star. A nearby Earth-mass exoplanet discovered An exoplanet with an Earth-like mass has been discovered orbiting the nearby star α Centauri B. The planet is not in the habitable zone — it is much nearer to its star than we are to the Sun, orbiting at only about 0.04 astronomical units from its star (an astronomical unit is the mean distance between Earth and the Sun). Statistical studies suggest that low-mass planets form preferentially in multi-planet systems, so it is possible that other planets are orbiting α Centauri B, perhaps in its habitable zone.