It was discovered on 29 September 2003, by astronomers of the Lowell Observatory Near-Earth-Object Search at Anderson Mesa Station near Flagstaff, Arizona.

[1] Patrick Taylor of Arecibo Observatory suggested it could be a target for a future robotic mission.

[citation needed] 2003 SD220 passed its closest distance of 7.34 LD (0.01899 AU) on 22 December 2018.

[8] Its peak brightness was about 13.1 magnitude on 16 December 2018, moving south from Ursa Major and Boötes into Ophiuchus at closest approach and into Sagittarius.

It was observed by the Goldstone Solar System Radar from November to December 2021.