Armstrong, Aldrin stayed on Moon for 21.5 hours after landing

Astronauts Neil Armstrong and Buzz Aldrin stayed on the Moon's surface for around 21.5 hours after stepping on the lunar surface on July 21, 1969. Michael Collins, the mission's third astronaut, orbited the Moon alone in 'Columbia' for that duration. During each orbit, Collins experienced 48 minutes of zero contact with Earth while crossing the dark side of the Moon.