Chapter 17, Routine Interplanetary Violence, Chapter 18, The Marsh of Camarina Summary and Analysis

The rings of Saturn are a "vast horde of tiny ice worlds" and are bound to Saturn by its gravity. It is not clear why Saturn has rings. The ring systems, Jupiter, Saturn, Uranus, and Neptune, are mysteries. They also differ from one another. Some think the rings came from planetary tides and Sagan explains the potential mechanism. Some rings will form into planets but others will not due to a lack of mass. Sometimes planetary collisions may produce the relevant matter.

Whatever the story is, the Solar System seems to have been produced through extraordinary but regular interplanetary violence. Again, there is no hint of intelligence here, in Sagan's view. As time goes on, the number of asteroids shrinks through gravity and collision. We...