On the origin of the asteroids

Abstract

Photometric measurements of asteroids show that they rotate with periods of 5-10 hr. The rotational period does not vary in a systematic way with the size of the asteroid, and it is of the same order as the periods of the ordinary planets. It is pointed out that it is difficult to reconcile this fact with the current hpothesis that the asteroids are fragments of a "broken-up planet". Instead one must assume that there must be some process by which all planets-including asteroids-obtain this period of rotation when they are formed by condensation of interplanetary material. © 1964.