Kelley and I were talking about space last night, partly because the Cassini probe completed a dive between Saturn and its rings, and partly because Jace has been been learning about planets. We watched this excellent video, which starts out comparing the sizes of various planets and stars, then zooms out to compare the scale of galaxies and more.

Such mind-boggling vastness can make one feel very small, so naturally we tried to counter that by thinking of the tiniest things in...