| Resonant effects can be clearly seen in the radial distribution of the asteroids. Some orbital resonances are destabilizing, creating minima in the distribution, called "Kirkwood gaps," after Daniel Kirkwood, the astronomer who first recognized them. The main asteroid belt is bounded by the 4:1 and 2:1 orbital resonances with Jupiter. The stable 3:2 and 1:1 resonances account, respectively, for the Hilda family asteroids and Jupiter Trojans. One astronomical unit is the Earth-Sun distance. (Distribution of asteroids courtesy of the Minor Planet Center.) |
