The idea of an asteroid from outer space crashing into Earth has captured the imaginations of science fiction directors for decades. But here at NASA, we take potentially hazardous near-Earth objects seriously. We have a planetary defense office that plans for every scenario—we’ve even practiced nudging an asteroid off course with spacecraft. But there are tens of thousands of objects in near-Earth space, and the first step in protecting against potential impacts is spotting, tracking and managing every single one of them. Learn how NASA does just that from Joe Masiero, a scientist on the asteroid survey mission NEOWISE. Then, join friend of the show Latif Nasser, co-host of the podcast Radiolab, to untangle the mystery of a strange space rock that’s not quite a moon but not quite a normal asteroid, either.