ヤルコフスキー効果
No observations of Apophis were made between January 2015 and February 2019, and then observations started occurring regularly in January 2020. In March 2020, astronomers David Tholen and Davide Farnocchia measured the acceleration of Apophis due to the Yarkovsky effect for the first time, significantly improving the prediction of its orbit past the 2029 flyby. Tholen and Farnocchia found that the Yarkovsky effect caused Apophis to drift by about 170 meters per year. In late 2020, Apophis approached the Earth again. It passed from Earth on March 6, 2021, brightening to +15 mag at the time. Radar observations of Apophis were planned at Goldstone in March 2021. The asteroid has been observed by NEOWISE (in December 2020) and by NEOSSat (in January 2021).