21 Lutetia
Rosetta image of 21 Lutetia at closest approach | |
| Discovery | |
|---|---|
| Discovered by | Hermann M. S. Goldschmidt |
| Discovery date | 15 November 1852 |
| Designations | |
| (21) Lutetia | |
| Pronunciation | /ljuːˈtiːʃiə/ |
Named after | Paris (Latin: Lutētia) |
| Main belt | |
| Adjectives | Lutetian |
| Orbital characteristics | |
| Epoch May 31, 2020 (JD 2459000.5) | |
| Aphelion | 2.833 AU (423.8 million km) |
| Perihelion | 2.037 AU (304.7 million km) |
| 2.435 AU (364.3 million km) | |
| Eccentricity | 0.16339 |
| 3.80 yr (1388.1 d) | |
| 87.976° | |
| Inclination | 3.064° |
| 80.867° | |
| 249.997° | |
| Physical characteristics | |
| Dimensions | (121±1) × (101±1) × (75±13) km |
| 49±1 km | |
| Volume | (5.0±0.4)×1014 m3 |
| Mass | (1.700±0.017)×1018 kg |
Mean density | 3.4±0.3 g/cm3 |
| 0.3402 d (8.1655 h) | |
| 96° | |
North pole right ascension | 51.8 ± 0.4° |
North pole declination | +10.8 ± 0.4° |
| 0.19 ± 0.01 (geometrical) 0.073 ± 0.002 (bond) | |
| Temperature | 170–245 K |
| M (Tholen) | |
| 9.25 to 13.17 | |
| 7.29 | |
21 Lutetia is a large M-type asteroid in the main asteroid belt. It measures about 100 kilometers in diameter (120 km along its major axis). It was discovered in 1852 by Hermann Goldschmidt, and is named after Lutetia, the Latin name of Paris.
Lutetia has an irregular shape and is heavily cratered, with the largest impact crater reaching 45 km in diameter. The surface is geologically heterogeneous and is intersected by a system of grooves and scarps, which are thought to be fractures. It has a high overall bulk density, suggesting that it is made of metal-rich rock.
The Rosetta probe passed within 3,162 km (1,965 mi) of Lutetia in July 2010. It was the largest asteroid visited by a spacecraft until Dawn arrived at Vesta in July 2011, and it is currently the 3rd largest asteroid to have ever been imaged in high quality by a spacecraft (after Vesta and Ceres).