253 Mathilde
Mathilde (minor planet designation: 253 Mathilde) is an asteroid in the intermediate asteroid belt, approximately 50 kilometers in diameter, that was discovered by Austrian astronomer Johann Palisa at Vienna Observatory on 12 November 1885. It has a relatively elliptical orbit that requires more than four years to circle the Sun. This tumbling asteroid has an unusually slow rate of rotation, requiring 17.4 days to complete a 360° revolution about its axis. It is a primitive C-type asteroid, which means the surface has a high proportion of carbon; giving it a dark surface that reflects only 4% of the light that falls on it.
253 Mathilde as seen by NEAR in 1997 | |
| Discovery | |
|---|---|
| Discovered by | J. Palisa |
| Discovery site | Vienna Obs. |
| Discovery date | 12 November 1885 |
| Designations | |
MPC designation | (253) Mathilde |
| Pronunciation | /məˈtɪldə/ |
Named after | Mathilde Loewy |
Alternative designations | A885 VA, 1915 TN 1949 OL1 |
Minor planet category | Main belt |
| Orbital characteristics | |
| Epoch 31 July 2016 (JD 2457600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 130.38 yr (47622 d) |
| Aphelion | 3.35003411 AU (501.157970 Gm) |
| Perihelion | 1.9467702 AU (291.23268 Gm) |
Semi-major axis | 2.648402147 AU (396.1953219 Gm) |
| Eccentricity | 0.26492652 |
Orbital period (sidereal) | 4.31 yr (1574.3 d) |
Average orbital speed | 17.98 km/s |
Mean anomaly | 170.584348° |
Mean motion | 0° 13m 43.248s / day |
| Inclination | 6.7427122° |
Longitude of ascending node | 179.58936° |
| 157.39642° | |
| Earth MOID | 0.939032 AU (140.4772 Gm) |
| Jupiter MOID | 2.06073 AU (308.281 Gm) |
| TJupiter | 3.331 |
| Physical characteristics | |
| Dimensions | 52.8 km (66×48×46 km) |
| Mass | (1.033±0.044)×1017 kg |
Mean density | 1.3 g/cm3 |
Equatorial surface gravity | 0.00989 m/s2 |
Equatorial escape velocity | 22.9 m/s |
Synodic rotation period | 417.7 h (17.40 d) 17.406 ± 0.010 d (17 d 9 h 45 min) |
| 0.0436±0.004 | |
| Temperature | ≈ 174 K |
| Cb | |
| 10.3 | |
Mathilde was visited by the NEAR Shoemaker spacecraft during June 1997, on its way to asteroid 433 Eros. During the little flyby, the spacecraft imaged a hemisphere of the asteroid, revealing many large craters that had gouged out depressions in the surface. It was the first carbonaceous asteroid to be explored and, until 21 Lutetia was visited in 2010, it was the largest asteroid to be visited by a spacecraft.