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Apollo 11 Moon landing
July 20, 1969· Event· Americas & Oceania
Well documentedSolid records, physical evidence or scientific consensus.
On July 20, 1969, Neil Armstrong and Buzz Aldrin of Apollo 11 became the first people to walk on the Moon.
See it on the History map →What happened
Apollo 11 launched on a Saturn V rocket on July 16, 1969. Michael Collins stayed in orbit while Armstrong and Aldrin landed the lunar module Eagle in the Sea of Tranquility, with under a minute of fuel to spare. 'That's one small step for man, one giant leap for mankind,' Armstrong said. They spent about two and a half hours outside, collected 21.5 kg of rock and returned safely on July 24. Five more landings followed through 1972.
Why it matters
It won the space race for the US and was watched live by an estimated 600 million people, a shared moment for much of humanity.
How we know
Hundreds of kilograms of Moon rock studied worldwide, mirrors left on the surface that observatories still bounce lasers off, and photos of the landing sites from later orbiters.
Connections (2)
▸Space race climaxed with the Apollo 11 Moon landingWell documented
The connection
After Gagarin's 1961 flight, Kennedy chose the Moon as a goal the US could win. NASA's Apollo program employed about 400,000 people at its peak and cost about $25 billion then, roughly $250 billion today. Apollo 11's 1969 landing effectively ended the race, and the Soviets quietly abandoned their crewed Moon program.
When and how
Kennedy's speech to Congress, May 25, 1961; Apollo 11 landing, July 20, 1969; the Soviet N1 Moon rocket failed four times, 1969–1972.
How we know
NASA budgets and records document Apollo; the Soviet program was confirmed after the USSR admitted it in 1989.
Debates and open questions
Whether the Soviets could have landed first with more money, and whether crewed landings were the best use of it, are debated.
▸Apollo 11 Moon landing returned rocks that hold clues to the Birth of the MoonMostly agreed
The connection
Apollo astronauts brought back 382 kg of Moon rock. It is dry, low in iron, and its oxygen isotopes nearly match Earth's. These clues led scientists in 1975 to propose the giant-impact theory: a Mars-sized body hit the young Earth, and the debris formed the Moon. The Curious Science map covers it in depth.
When and how
Six Apollo landings, 1969–1972; samples studied in Houston and labs worldwide; William Hartmann and Donald Davis published the impact idea in 1975.
How sure are we?
Lab analysis of the samples and computer simulations of the impact support the theory, now the leading explanation.
Debates and open questions
The rocks match Earth too closely: simple models predict more material from the impactor. Variants, such as a hotter or faster collision, try to explain it.