We tend to think of Earth as almost impossibly rare, but a University of British Columbia study using Kepler data estimated that the Milky Way could contain as many as six billion rocky, roughly Earth-sized planets orbiting in the habitable zones of stars like our Sun — not proven Earth twins, but billions of worlds with at least the basic size, star, and distance that make Earth possible.

Earth can feel like an exception so complete that no statistic should be able to touch it. It has oceans, continents, a long-lived atmosphere, plate tectonics, a stabilising Moon, a magnetic field and a history that, at least here, eventually produced forests, animals, language and spacecraft. But one of the quieter lessons of the Kepler [...] The post We tend to think of Earth as almost impossibly rare, but a University of British Columbia study using Kepler data estimated that the Milky Way co