2018 PD20 is a small asteroid, classified as a near-Earth object of the Apollo group, approximately 9–20 meters (30–66 feet) in diameter. On 11 August 2018, it was first observed by ATLAS at the Mauna Loa Observatory on Hawaii (T08), when it passed 33,500 kilometers (20,800 miles) from the Earth. This is notable because it came within a tenth of the lunar distance, or 0.10 LD which is closer to Earth than satellites in a geostationary orbit. These have an altitude of 0.11 LD, about 36,000 km (22,000 mi), approximately 3 times the width of the Earth.