Scientific American reports: It was just over 20 years ago — a blink of a cosmic eye — that astronomers found the first planets orbiting stars other than our Sun. All these new worlds were gas-shrouded giants like Jupiter or Saturn and utterly inhospitable to life as we know it — but for years each discovery was dutifully reported as front-page news, while scientists and the public alike dreamed of a day when we would find a habitable world. An Earth-like place with plentiful surface water, neither frozen nor vaporized but in the liquid state so essential to life. Back then the safe bet was to guess that the discovery of such a planet would only come after many decades, and that when a promising new world’s misty shores materialized on the other side of our telescopes, it would prove too faraway and faint to study in any detail.
Evidently the safe bet was wrong. On Wednesday astronomers made the kind of announcement that can only occur once in human history: the discovery of the nearest potentially habitable world beyond our solar system. This world may be rocky like ours and whirls in a temperate orbit around the Sun’s closest stellar neighbor, the red dwarf star Proxima Centauri just over four light-years away. Their findings are reported in a study in the journal Nature.
Although technically still considered a “candidate” planet awaiting verification, most astronomers consulted for this story believe the world to be there. Scarcely more than the planet’s orbital period and approximate mass are known, but that is enough to send shivers down spines. Proxima Centauri shines with only about a thousandth of our Sun’s luminosity, meaning any life-friendly planets must huddle close. The newfound world, christened “Proxima b” by scientists, resides in an 11.2-day orbit where water — and thus the kind of life we understand — could conceivably exist. And it is likely to be little more than one-third heavier than Earth, suggesting it offers a solid surface upon which seas and oceans could pool. In a feat of discovery that could reshape the history of science and human dreams of interstellar futures, our species has uncovered a potentially habitable planet right next door. [Continue reading…]