53: ’Tis the season(ality)

Life on Earth changes dramatically with the seasons — so much so that spotting Earth’s seasons from space is easy. Spring and summer are generally green, Autumn turns brown, and winter is white — in some parts of the world anyway. Could you detect seasons on exoplanets? And if so, could you use that as a signature of extra-terrestrial life? A tip from one of our Patreon patrons sent us in search of exoplanet seasonality, via all sorts of other biosignatures, from the technological (UFOs?), to the physical (fossils), to the atmospheric (chemicals in the atmosphere), and finally to the time-dependent (seasons).