The orbits of 1900 minor planets have been accurately established. The results of a statistical survey of the numerous faint asteroids are available. Special types of orbital motion are revealed in a comparison of the range of variation of heliocentric distance for minor and major planets. New methods are provided for determining asteroid diameters. The resulting low mean density of Ceres is comparable to the densities of some types of carbonaceous chondrites. Measurements of reflectivity as a function of wavelength allow another comparison of asteroids and meteorites. The evolutionary process that led to the present population of minor planets is probably different for objects on regular and unusual orbits.
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