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Image courtesy of ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA.
Asteroid Lutetia
Lutetia is a medium-sized asteroid. It orbits the Sun in the main asteroid belt between the planets Mars and Jupiter. Its official name is "21 Lutetia" because it was the 21st asteroid discovered. Lutetia was discovered by Hermann Goldschmidt from the balcony of his apartment in Paris in 1852. Lutetia is the Latin name for Paris.
This lumpy object is about 96 km (60 miles) in diameter. It isn't a perfect sphere, though. Lutetia is 132 km (82 miles) across one way, but only about 76 km (47 miles) long in another direction.
Astronomers aren't quite sure what Lutetia is made of. It may have more metal in it than most asteroids. However, some observations of Lutetia show that it is mostly rock, like most other asteroids. The material that an asteroid is made of gives us clues about how it formed and what has happened to it over the history of the Solar System.
The European space probe Rosetta flew past Lutetia in July 2010. Rosetta gave us our first good look at the asteroid. Lutetia is the largest asteroid visited by a spacecraft so far. Rosetta was zooming along at a speed of 15 km/s (9 miles/sec or more than 33,000 mph) when it flew by Lutetia! Rosetta sent some great pictures and lots of other data back to Earth. After its visit to Lutetia, Rosetta continued on its long journey to land on a comet in 2014.
