MANY of the asteroids in our solar system are lined up in formation – spinning at the same speed with their axes pointing in the same direction. But there’s no eerie guiding force at work. The alignment of the rocks is due to an obscure phenomenon called the Yarkovsky effect, which is caused by sunlight.
Astronomers had assumed that the main force that sets asteroids spinning is impacts by other asteroids. Collisions would knock the asteroids in random directions, resulting in random spins. But in the Koronis family of asteroids, the spins cluster into groups. David Vokrouhlicky of Charles University in…
