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Pandora
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Pandora is heavily cratered and, as revealed by the Cassini probe during its passage of the moon at a distance of 52,000 km on September 5, 2005, there are small grooves and ridges in the dust-fine icy material that has collected over the craters. The two largest craters identified measure about 30 km (19 miles) across.
Pandora and Prometheus, the inner shepherd of the F-ring, both follow chaotic orbits as a result of their gravitational interaction. Each time Pandora passes inside Prometheus, which happens about every 28 days, the two moons give each other a gravitational kick. Because neither moon's orbit is quite circular, the distance between them on those occasions – hence the strength of the kick - varies. The perturbations lead to changes in motion that are not periodic or predictable. This is the first observation ever of chaotic orbital motions in the Solar System. A larger moon of Saturn, Hyperion, had earlier been found to have chaotic rotation around its axis.
| Discovery | 1980, by S. Collins from Voyager 1 data |
| Semimajor axis | 141,720 km (88,080 miles) |
| Diameter | 103 × 80 × 64 km (64 × 50 × 40 miles) |
| Mean density | 0.5 g/cm3 |
| Escape velocity | 0.019 km/s (68 km/h, 43 mph) |
| Orbital period | 0.629 days (15 hr 6 min.) |
| Orbital eccentricity | 0.004 |
| Orbital inclination | 0.05° |
| Visual albedo | 0.6 |
Related entry
• Saturn, moons
Related category
• PLANETS AND MOONS
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