Video: 'Relive Apollo 11 in Real Time!'

(Sunday, July 20, 1969, 20:17:40 Coordinated Universal Time) — American astronauts Neil A. Armstrong and Edwin “Buzz” Aldrin became the first human beings to land on another world today as Armstrong piloted the descent of the Apollo 11 lunar module, nicknamed “Eagle,” onto the surface of the Moon.

Video: '1969 Apollo 11 Moon Landing "The Eagle has landed" Lunar Module POV'

The “Eagle” touched down in the Mare Tranquillitatis, 9.3 miles south of a crater called “Sabine D,” which would later be renamed the Collins crater, named after the third member of the crew, Michael Collins, who continued to orbit the Moon in the command module “Columbia.”

Video: 'Apollo 11 Part 26 CBS News Coverage of The Moon Landing' (landing at 5:39)

Information available to the crew and mission controllers during the landing showed that the lunar module had enough fuel for another 25 seconds of powered flight before an abort without touchdown would have become unsafe, but post-mission analysis showed that the real figure was probably closer to 50 seconds.

Armstrong acknowledged Aldrin’s completion of the post landing checklist with “Engine arm is off,” before responding to the capsule communicator, Charles Duke, with the words, “Houston, Tranquility Base here. The Eagle has landed.”

Video: 'ABC News Coverage of Apollo 11 Part 12 (The Moon Landing)' (landing at 5:51)

Armstrong’s unrehearsed change of call sign from “Eagle” to “Tranquility Base” emphasized to listeners that landing was complete and successful.

Duke mispronounced his reply as he expressed the relief at Mission Control: “Roger, Twan— Tranquility, we copy you on the ground. You got a bunch of guys about to turn blue. We’re breathing again. Thanks a lot.”

The schedule for the mission called for the astronauts to follow the landing with a five-hour sleep period, but they chose to begin the preparations for the moonwalk early, thinking that they would be unable to sleep.