The Moon - a cold, airless ball of rock 50 times smaller than Earth - is our largest and closest celestial friend.
Taken by: William Anders of Apollo 8's crew
Date: 24 December 1968
NASA's famous 'Earthrise' image was taken as Apollo 8 astronauts Frank Borman, Jim Lovell, and William Anders swung around the Moon.
During a broadcast with Earth, Lovell said: "The vast loneliness is awe-inspiring and it makes you realise just what you have back there on Earth."
Its kinship with us is uncanny: the Moon formed after a Mars-size planet smacked into a proto-Earth some 4.5 billion years ago.
Taken by: Lunar Reconnaissance Orbiter (LRO)
Date: 12 October 2015
Launched by NASA in 2009, LRO normally stares down at the cratered surface of the Moon - but took a moment to snap this modern-day 'Earthrise' composite photo.
We know this only because, since the 1950s, nations all around the world have launched people and robots there.
Taken by: Lunar Orbiter 1
Date: 23 August 1966
In 2008, the Lunar Orbiter Image Recovery Project (LOIRP) released this high-resolution version of a Lunar Orbiter 1 photo of Earth from the Moon, which was taken on Aug. 23, 1966.
Lunar Orbiter 1 took this photo while scouting for places astronauts might land on the Moon.
Because 1960s technology couldn't access the full depth of image data that NASA had recorded on analog tapes, however, the Lunar Orbiter Image Recovery Project recently recovered this version of the famous image.
The full-size version is large enough to print as a billboard.
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