No matter how you measure it, whether you measure the amount of mass or you measure the number of bodies, most of our solar system exists out beyond the orbits of the asteroids. So we could not have claimed to know our own solar system until Voyager had toured the giant planets.

Even by the diverse standards of Saturn's satellites, Enceladus was an outlier. Its icy surface was as white and bright as fresh snow, and whereas the other airless moons were heavily pocked with craters, Enceladus was mantled in places with extensive plains of smooth, uncratered terrain, a clear sign of past internally driven geologic activity.

When the Voyager 2 spacecraft sped through the Saturnian system more than a quarter of a century ago, it came within 90,000 kilometers of the moon Enceladus. Over the course of a few hours, its cameras returned a handful of images that confounded planetary scientists for years.

Carolyn Porco Quotes