Pieter de Hooch was a Dutch Golden Age painter famous for his genre works of quiet domestic scenes with an open doorway. He was a contemporary of Jan Vermeer in the Delft Guild of St. Luke, with whom his work shares themes and style.

Grand Duke Nicholas Nikolaevich of Russia was a Russian general in World War I. A grandson of Emperor Nicholas I of Russia, he was commander in chief of the Russian Imperial Army units on the main front in the first year of the war, during the reign of his nephew, Nicholas II. He proved incompetent in strategy, tactics, logistics and coordination with the government. After the Gorlice–Tarnów Offensive in 1915, Tsar Nicholas replaced the Grand Duke as commander-in-chief of the army. He later was a successful commander-in-chief in the Caucasus region. He was briefly recognized as Tsar, Emperor of Russia in 1922 in areas controlled by the White Armies movement in the Russian Far East.

Gemini 4 was the second crewed spaceflight in NASA's Project Gemini, occurring in June 1965. It was the tenth crewed American spaceflight. Astronauts James McDivitt and Ed White circled the Earth 66 times in four days, making it the first US flight to approach the five-day flight of the Soviet Vostok 5. The highlight of the mission was the first space walk by an American, during which White floated free outside the spacecraft, tethered to it, for approximately 20 minutes. Both of these accomplishments helped the United States overcome the Soviet Union's early lead in the Space Race.

The flight also included the first attempt to make a space rendezvous as McDivitt attempted to maneuver his craft close to the Titan II upper stage which launched it into orbit, but this was not successful.

The flight was the first American flight to perform many scientific experiments in space, including use of a sextant to investigate the use of celestial navigation for lunar flight in the Apollo program.