2020 OY4

 is a very small asteroid classified as a near-Earth object that passed within 21850 mi of the surface of Earth on July 28, 2020, with a fly-by speed of 7.7 mi per second. The car-sized asteroid posed no risk of impact to Earth, but it did pass within the orbit of satellites in the geostationary ring at 22236 mi above Earth's equator.

The asteroid was discovered July 26, 2020 using the Mount Lemmon Survey telescope in the Santa Catalina Mountains northeast of Tucson, Arizona. The next encounter closer than the Moon is predicted to occur July 30, 2055 at a distance of 124000 mi or more.