Jonathan Eastman Johnson was an American painter and co-founder of the Metropolitan Museum of Art, New York City, with his name inscribed at its entrance. He was best known for his genre paintings, paintings of scenes from everyday life, and his portraits both of everyday people and prominent Americans such as Abraham Lincoln, Nathaniel Hawthorne, Ralph Waldo Emerson, and Henry Wadsworth Longfellow. His later works often show the influence of the 17th-century Dutch masters, whom he studied in The Hague in the 1850s; he was known as The American Rembrandt in his day.

Pál Maléter was the military leader of the 1956 Hungarian Revolution.

Maléter was born to Hungarian parents in Eperjes, a city in Sáros County, in the northern part of Historical Hungary, today Prešov, Slovakia. He studied medicine at the Charles University, Prague, before moving to Budapest in 1938, going to the military academy there. He fought on the Eastern Front of World War II for Axis, until captured by the Red Army. He became a Communist, trained in sabotage, fought against the Germans in Transylvania and was sent back to Hungary, where he was noted for his courage and daring.

In 1956 he was a colonel and the commander of an armoured division stationed in Budapest when he was sent to suppress the Hungarian Uprising, but on making contact with the insurgents he decided to join them, helping to defend the Kilian Barracks. He was the most prominent member of the Hungarian military to change sides, allying himself with the insurgents rather than with Gerő's communist government.

The Chernobyl disaster was caused by a nuclear accident that occurred on Saturday 26 April 1986, at the No. 4 reactor in the Chernobyl Nuclear Power Plant, near the city of Pripyat in the north of the Ukrainian SSR. It is considered the worst nuclear disaster in history and was caused by one of only two nuclear energy accidents rated at seven—the maximum severity—on the International Nuclear Event Scale, the other being the 2011 Fukushima Daiichi nuclear disaster in Japan.

The accident started during a safety test on an RBMK-type nuclear reactor, which was commonly used throughout the Soviet Union. The test was a simulation of an electrical power outage to aid the development of a safety procedure for maintaining reactor cooling water circulation until the back-up electrical generators could provide power. This gap was about one minute and had been identified as a potential safety problem that could cause the nuclear reactor core to overheat. It was hoped to prove that the residual rotational energy in a turbine generator could provide enough power to cover the gap. Three such tests had been conducted since 1982, but they had failed to provide a solution.