Growth and Evolution of Asteroids

Asteroids are what is left of the precursors to the terrestrial planets. They are stunning in their diversity, ranging from charcoal-black worlds the size of a hilltop, spinning like a carnival ride, to dog-bone-shaped metallic remnants of some cataclysmically disrupted planetary core, to worlds as stately as Ceres and Vesta (and fragments thereof), to garden-variety fractured and blocky nuggets that dominate near-Earth space. Asteroid belts are common around Sun-like stars. When properly seen as unaccreted residues, as scraps on the floor of the planetary bakery, the diversity of asteroids can be fully appreciated, for to paraphrase Tolstoy, accreted planets are all alike; every unaccreted planet is unaccreted in its own way.