Lutetia
Key facts
- What it is
- Large main-belt asteroid
- Size
- About 100 km across
- Discovered
- 1852, by Hermann Goldschmidt
- Spacecraft
- Rosetta fly-by, 2010
- Orbit group
- Main-belt Asteroid
- Average distance from the Sun
- 2.43 au (about 360 million km)
- Time to go round the Sun
- 3.8 years
- Closest and farthest from the Sun
- 2.03 to 2.84 au
- Tilt of its orbit
- 3.1°
- Spins once every
- 8.2 hours
An au (astronomical unit) is Earth's average distance from the Sun, about 150 million km. Orbit figures are from open tracking data, figures last updated 1 Nov 2026.
Lutetia is one of the largest asteroids photographed close up by a spacecraft. The European Space Agency's Rosetta flew past it on 10 July 2010 at a distance of about 3,200 kilometres, on the way to the comet it was sent to study. The images showed an irregular body about 120 kilometres long and around 100 kilometres across, with a long and complicated history.
Parts of Lutetia's surface are densely cratered and very old, perhaps dating back close to the beginning of the Solar System. Other areas are smoother and younger, covered by a thick layer of fine dust and broken rock. There are landslides, grooves and boulders, and one large, bowl-shaped region that may be what is left of a giant ancient crater.
Rosetta's fly-by also allowed Lutetia's mass to be measured, giving a density of about 3.4 grams per cubic centimetre. That is high for an asteroid and suggests a mostly solid interior, perhaps with some metal. Lutetia's colour and the way it reflects light have been compared with enstatite chondrites, primitive meteorites formed in oxygen-poor conditions close to the young Sun. If that link is right, Lutetia may be a piece of the original material from which the inner planets, Earth included, were built.
Lutetia was discovered in 1852 by Hermann Goldschmidt, a German-born painter and astronomer, from his balcony in Paris. Its name comes from Lutetia, the Roman name for the city.