Between roughly 1645 and 1715, the Sun’s sunspots all but vanished. In one 27-year window from 1672 to 1699, astronomers worldwide logged fewer than 50 spots, compared with the 40,000 to 50,000 you would expect today. This episode explores the Maunder Minimum, from Gustav Sporer’s discovery of the gap in the 1880s to the meticulous latitude mapping by Edward and Annie Russell Maunder in the 1890s, published under Edward’s name alone because Annie was barred from a degree, and John A. Eddy’s 1976 paper that finally named the phenomenon.

The hosts address the skeptic’s question of whether 17th-century telescopes were simply inadequate, citing Cassini’s systematic daily observations at Paris that caught a single sunspot in 1680. They explain differential rotation and the twisted magnetic engine behind sunspots, the 1706 eclipse paintings by Maria Clara Eimmart rediscovered in 2012 that showed a structureless corona, the real but limited role of the Sun in the Little Ice Age, and how reduced UV output weakened the jet stream to funnel Arctic air into northern Europe during the Great Frost of 1708 and 1709.

• Why the equator’s 24.7-day rotation versus the poles’ 33 days winds up the Sun’s magnetic field like rubber bands
• How volcanoes rather than the quiet Sun were likely the main trigger for the Little Ice Age
• How carbon-14 in tree rings and beryllium-10 in ice cores reveal 18 grand solar minima in the last 8,000 years
• Why aurorae kept appearing during the Maunder Minimum even though sunspots had vanished
• What a future grand minimum could mean for satellites, the jet stream, and a civilization built during a hyperactive Sun