In November 1998, astronomers at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, found a small moon orbiting Eugenia. This was the first time a moon orbiting an asteroid had been found by a ground-based telescope. Eugenia's moon has been named (45) Eugenia I Petit-Prince, after Empress Eugenia's son, the Prince Imperial. The moon is much smaller than Eugenia, about 13 km in diameter, and takes five days to complete an orbit around it.