On This Day: August 21

August 21 begins with four empty hooks in the Louvre, moves to a presidential signature that made Hawaii the fiftieth U.S. state, and ends beside a lake in Cameroon where an invisible cloud changed an entire valley. The episode asks how a quiet moment can become a public turning point.

The Mona Lisa disappears. On August 21, 1911, three men dressed as janitors removed Leonardo da Vinci’s Mona Lisa from the closed Louvre and walked out with it under a smock. The painting was still relatively obscure beyond the French art world; the publicity around its two-year disappearance helped turn it into an international celebrity. 1

Hawaii becomes a state. On August 21, 1959, President Dwight D. Eisenhower signed the proclamation admitting Hawaii as the fiftieth state. That legal milestone followed a longer history of U.S. economic and political influence, the 1893 overthrow of the Hawaiian monarchy, territorial status in 1900, and a 1959 statehood vote. 23

Lake Nyos releases a hidden danger. On August 21, 1986, a limnic eruption released carbon dioxide that had accumulated in the deep water of a volcanic lake in Cameroon. The resulting cloud killed roughly 1,700 to 1,800 people and thousands of animals. Scientists still debate the immediate trigger, while controlled degassing and warning systems followed. 4