2021 UA1 is a small (~2 meter) near-Earth object that passed about 3047 km from the surface of Earth while passing over Antarctica on 25 October 2021 around 03:07 UT.[5][a]Given the small size of the asteroid it only reached the brightness of Pluto at around apparent magnitude 14.[5] Since it approached from the direction of the Sun, it was not discovered until 4 hours after closest approach.[1]
| Asteroid | Date | Distance from surface of Earth | Uncertainty in approach distance | Reference |
|---|---|---|---|---|
| 2020 VT4 | 2020-11-13 | 374 km | ±25 km | data |
| 2020 QG | 2020-08-16 | 2946 km | ±20 km | data |
| 2021 UA1 | 2021-10-25 | 3047 km | ±20 km | data |
| 2011 CQ1 | 2011-02-04 | 5481 km | ±5 km | data |
| 2019 UN13 | 2019-10-31 | 6242 km | ±200 km | data |
| 2008 TS26 | 2008-10-09 | 6259 km | ±1000 km | data |
| 2004 FU162 | 2004-03-31 | 6542 km | ±15000 km | data |