For 59 days before the encounter, the asteroid would not hold still. Lucy’s long-range camera kept watching this faint smudge of reflected light from millions of kilometres out, and the brightness rose and fell the way it should for a rotating lump of rock, except the pattern never quite repeated. One period of about 253 hours, fine. But buried underneath sat a second rhythm, roughly 455 hours, the two beating again New! Sign up for our email newsletter on Substack.