For months, YR4 carried a remarkable question: would its 2032 path cross the Moon? The estimated chance reached about 4.3%, a scientifically meaningful result that sent astronomers after one of the faintest asteroid targets Webb had ever attempted.
Webb found it during two narrow observing windows in February 2026. Those measurements sharpened the route dramatically. YR4 is now expected to skim past at roughly 13,200 miles (21,200 kilometers) above the lunar surface.
For scale, that gap is only about one-and-two-thirds Earth diameters. Webb did not merely settle a probability; it turned a barely visible speck into a forecast precise enough to describe a close lunar flyby nearly seven years ahead. That is the kind of cosmic appointment worth circling on the calendar.