4769 Castalia
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| 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 (previously known by the provisional designation 1989 PB) was the first asteroid to be directly imaged. 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.
[edit] 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 m diameter pieces held together by their weak mutual gravity. Since then radar observations of other asteroids have found other contact binaries.
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[edit] External links
| Minor planets | ||
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| Previous minor planet | 4769 Castalia | Next minor planet |
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| Vulcanoids | Near-Earth asteroids | Main belt | Jupiter Trojans | Centaurs | Damocloids | Comets | Trans-Neptunians (Kuiper belt · Scattered disc · Oort cloud) |
| For other objects and regions, see: asteroid groups and families, binary asteroids, asteroid moons and the Solar system For a complete listing, see: List of asteroids. See also Pronunciation of asteroid names and Meanings of asteroid names. |
