4769 Castalia
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4769 Castalia
| Orbital characteristics | |
|---|---|
| Orbit type | Near-Earth, Venus-crosser asteroid, Mars-crosser asteroid |
| Semimajor axis | 1.063 AU |
| Eccentricity | 0.4831 |
| Orbital period | 1.10 year |
| Inclination | 8.89° |
| Physical characteristics | |
| Diameter | 1.8×0.8 km |
| Mass | 5.0×1011 kg |
| Density | 2.1 g/cm³ |
| Rotation period | 4 h |
| Spectral class | S |
| Albedo | ? |
| History | |
| Discoverer | E. F. Helin, August 9, 1989 |
The asteroid 4769 Castalia (
/kɨˈsteɪliə/ kə-STAY-lee-ə; previously known by the provisional designation 1989 PB) was the first asteroid to be modeled by radar imaging. It is an Apollo, Mars- and Venus-crosser asteroid. It was discovered on August 9, 1989, by Eleanor F. Helin (Caltech) on photographic plates taken at Palomar Observatory. It is named after Castalia, a nymph in Greek mythology.
General information
Castalia's orbit took it within eleven lunar distances of Earth, allowing it to be observed with radar from the Arecibo Observatory by Scott Hudson (Washington State University) and Steven J. Ostro (JPL). The data allowed Hudson et al. to produce a three-dimensional model of the object.
Castalia has a peanut shape, suggesting two ~800-meter-diameter pieces held together by their weak mutual gravity. Since then radar observations of other asteroids have found other contact binaries.
See also
External links
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