45 Eugenia
 CFHT image of Eugenia and Petit-Prince | |
| Orbital characteristics 1 | |
|---|---|
| Orbit type | Main belt |
| Semimajor axis | AU |
| Perihelion distance | AU |
| Aphelion distance | AU |
| Orbital period | years |
| Inclination | 6.61° |
| Eccentricity | 0.083 |
| Physical characteristics | |
| Diameter 1 | km |
| Mass 3 | 18 kilogram>kg |
| Density 3 | g/cm³ |
| Rotation period 3 | hours |
| Spectral class | F |
| Abs. magnitude 1 | 7.46 |
| Albedo 4 | 0.040 |
| History 2 | |
| Discoverer | H. Goldschmidt, 1857 |
| Satellites | |
| Name | Petit-Prince |
45 Eugenia is a large Main belt asteroid. It is famed as one of the first asteroids to be found to have a moon orbiting it.
Eugenia was discovered in 1857 by Hermann Goldschmidt. It was named after Empress Eugenia di Montijo, the wife of Napoleon III, and was the first asteroid to be named after a real person, rather than a figure from classical legend (although there had been controversy about whether 12 Victoria was really named for the mythological figure or for Queen Victoria).
Eugenia is a large asteroid, with a diameter of 214 km. It is an F-type asteroid, which means that it is very dark in colouring (darker than soot) with a carbonaceous composition. Like Mathilde, its density appears to be unusually low, indicating that it may be a loosely-packed rubble pile, not a monolithic object.
In 1998, astronomers at the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, discovered a small moon orbiting Eugenia. This was the first time an asteroidal moon had been discovered by a ground-based telescope. Eugenia's moon has been named 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.