45 Eugenia
Discovery and Naming
The asteroid 45 Eugenia was discovered on June 28, 1857, by French astronomer Jean Chacornac. It was the 45th asteroid to be discovered, hence the number in its name. The asteroid was named after Empress Eugénie de Montijo, the wife of Napoleon III, who was the then ruler of France.
Physical Characteristics
45 Eugenia is a large main-belt asteroid that measures about 214.8 kilometers in diameter. It is classified as an F-type asteroid, which means it is dark in color and has a carbonaceous composition. The asteroid's surface is believed to be covered with a layer of fine dust, known as regolith.
Orbit and Rotation
45 Eugenia orbits the sun at an average distance of 2.72 astronomical units (AU), taking about 4.49 Earth years to complete one orbit. The asteroid's orbit is slightly elliptical, with an eccentricity of 0.083. It has an inclination of 6.61 degrees, meaning its orbit is tilted relative to the plane of the solar system.
The asteroid rotates on its axis once every 5.70 hours. This rapid rotation rate is relatively common among asteroids of its size.
Satellites
In 1998, astronomers discovered that 45 Eugenia has a small moon, later named Petit-Prince. This was the first time a moon had been discovered orbiting an asteroid. Petit-Prince is about 13 kilometers in diameter and orbits Eugenia at a distance of about 1,190 kilometers.
In 2004, a second, smaller moon was discovered orbiting 45 Eugenia. This moon, which has not yet been named, is about 6 kilometers in diameter and orbits at a distance of about 700 kilometers.
Exploration
As of now, no spacecraft has visited 45 Eugenia. However, it has been observed extensively from Earth using both ground-based and space-based telescopes.