Right now you are traveling at about 230 kilometers per second as the solar system orbits the center of the Milky Way, yet a single lap still takes roughly 225 million Earth years. This episode adopts that galactic year as a new yardstick for deep time, explaining why billion-year scales squish major events together while million-year scales produce numbers too large to feel.

Using this clock, the hosts place the Big Bang at 61 galactic years ago, the birth of the Milky Way at 60, a hypothesized merger with the Kraken galaxy at 39, and the formation of the Sun and Earth at 20. They trace the long slog from prokaryotes at 16 galactic years ago through the Great Oxidation Event, eukaryotes, multicellular life, and the first land plants, then the sprint through the Cambrian explosion, the Permian-Triassic extinction exactly one galactic year a ...