2021 UA1

 is a small (~2 meter) near-Earth object that passed about $1.35 AU$ from the surface of Earth while passing over Antarctica on 25 October 2021 around 03:07 UT. Given the small size of the asteroid it only reached the brightness of Pluto at around apparent magnitude 14. Since it approached from the direction of the Sun, it was not discovered until 4 hours after closest approach.

The 2021 Earth approach lifted the orbit and increased the orbital period from 356 days to 413 days. This changed it from an Aten asteroid to an Apollo asteroid.