A billion years ago, our Moon was closer to Earth than it is now. As a result, it appeared to be a much larger object in the sky. During that ancient era, if human beings had been around to witness such a sight, it would have been possible to see the entire Moon--not merely the one near side face that we see now. A billion years ago, it took our Moon only twenty days to orbit our planet, and Earth's own day was considerably shorter--only eighteen hours long. Stupendous, almost unimaginably enormous tides, that were more than a kilometer in height, would ebb and flow every few hours. However, things changed, as the lunar orbit around our primordial planet grew ever wider and wider. Annually, Earth's Moon moves about 1.6 inches farther out into space. Currently, the lunar rate of rotation, as well as the time it takes to circle our planet, are the same.
Some of these grads are aware that even if we could travel at warp 9 (Star Trek's imaginary multiplication of the speed of light) that it would take about one hundred thousand years to make the edge of the Milky Way Galaxy and upon return, the earth would be about 1.2 million years older than it is today. But why harp on the small stuff.
Cassini wasn't originally designed to spot signs of life in the Enceladus plume. In fact, planetary scientists didn't even know that the plume existed until after the spacecraft reached Saturn.