2020 PN1 is a sub-kilometer asteroid, classified as a near-Earth object of the Aten group, that is a temporary horseshoe companion to the Earth. There are dozens of known Earth horseshoe librators, some of which switch periodically between the quasi-satellite and the horseshoe co-orbital states.[6]
2020 PN1 was discovered on 12 August 2020 by L. Denneau, J. Tonry, A. Heinze, and H. Weiland observing
for the ATLAS-HKO Survey.[7] As of 20 January 2021, it has been observed 41 times with an observation arc of 361 days.[2]
2020 PN1 is currently an Aten asteroid (Earth-crossing but with a period less than a year). Its semi-major axis (currently 0.998105754 AU) is similar to that of Earth (0.999789 AU), but it has a moderate eccentricity (0.1269557) and low orbital inclination (4.80807°). It alternates between being an Aten asteroid and being an Apollo asteroid, although its orbital evolution is not fully stable and it can be considered as a temporary co-orbital companion to the Earth.[6]
2020 PN1 was pre-selected for an exploration by a Chinese mission of planetary defense including an impactor and a separate orbiter planned to launch in 2026.[8] However, in April 2023, the new target is 2019 VL5.[9]
Transient co-orbital asteroids Brasser, R., Innanen, K. A., Connors, M., Veillet, C., Wiegert, P., Mikkola, S., Chodas, P. W. 2004, Icarus, Vol. 171, Issue 1, pp. 102–109.
