Astronomers with the European Southern Observatory (ESO) have discovered an exoplanet orbiting a star just 11 light-years from our own Sun. It's roughly the size of Earth and is predicted to have a temperate climate, making it the second-nearest Earth-like planet known to exist.
As reported in the journal Astronomy & Astrophysics [PDF], the planet, dubbed Ross 128 b, circles the inactive red dwarf star Ross 128. Its orbit is 20 times closer to its star than Earth's is to the Sun, but the exoplanet receives only 1.38 times more radiation than we do. Ross 128 is much cooler than our Sun, and calmer than typical red dwarfs. Researchers estimate the planet's equilibrium temperature to be between -76°F and 68°F, making it temperate like our home planet.
The discovery was made by an international team of astronomers working with the ESO's High Accuracy Radial Velocity Planet Searcher (HARPS) at the La Silla Observatory in Chile. Popular Mechanics reports that instead of waiting for the exoplanet's shadow to pass across its star (what's known as the transit method), the scientists monitored the star's radial velocity. The gravitational pull of orbiting planets can cause their stars to wobble slightly, and by measuring these disturbances, researchers can estimate everything from a planet's mass to its location.
At just 11 light-years away, Ross 128 b is close, though not close enough to make it our nearest Earth-like neighbor. That title belongs to Proxima b, a planet similar in size, mass, and temperature to Earth that orbits the star Proxima Centauri. But Ross 128 is creeping closer to Earth, and in just 79,000 years, it could occupy the No. 1 slot. In the meantime, scientists will study Ross 128 b along with other close exoplanets to determine if they can support life.