The Chernobyl power plant in Ukraine exploded, killing 31 people and spreading contamination across Western Europe.
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The Treaty of London was signed by Italy, Britain, France, and Russia.
Astronomer Nicolaus Copernicus made his first observation of Saturn.
The official secret police force of Nazi Germany, the Gestapo, was established.
Ariel 1, the first British-American satellite, was launched from Cape Canaveral in Florida, US.
The Handmaid's Tale debuted on Hulu.
