S/2021 N 1

S/2021 N 1 is the smallest, faintest, and most distant natural satellite of Neptune known, with a diameter of around 16–25 km (10–16 mi). It was discovered on 7 September 2021 by Scott S. Sheppard, David J. Tholen, Chad Trujillo, and Patryk S. Lykawka using the 8.2-meter Subaru Telescope at Mauna Kea, Hawaii, and later announced on 23 February 2024.[1] It orbits Neptune in the retrograde direction at an average distance of over 50 million km (31 million mi) and takes about 27 Earth years to complete its orbit—the largest orbital distance and period of any known moon in the Solar System.