There should be billions of Earths out there. Why can’t we find them?
Earthlike planets are out there, hidden in our technological blind spots. ( NASA's Goddard Space Flight Center Conceptual Image Lab/)In 2009, the Kepler space telescope constantly watched over some 200,000 stars in our corner of the Milky Way. It was looking for where life might exist—by pinpointing small, rocky planets in the temperate zones of warm, yellow suns, and figuring out just how special Earth is in the grand scheme of things. While the mission revolutionized the study of exoplanets, those main objectives went largely unfulfilled. A mechanical failure cut short Kepler’s initial survey in 2013. Astronomers would later discover just a single Earthlike planet in its dataset.A decade later, researchers are finally closing in on some of the answers to the questions Kepler raised. Earthlike planets are probably rare, but not exceedingly so. Roughly one in five yellow stars could have one, according to a new analysis of Kepler’s...