The Blue Marble is an image of Earth taken on December 7, 1972, from a distance of about 29,000 kilometers (18,000 miles) from the planet's surface.[1][2][3] It was taken by the crew of the Apollo 17 spacecraft on its way to the Moon, and is one of the most reproduced images in history.[4][5][a]
References:
[1]^ "Apollo 17 PAO Mission Commentary Transcript" (PDF). NASA. 2001. p. 106. Retrieved May 11, 2017. SC: 'You're loud and clear, Bob, and could you give us our distance from the Earth?' ... CAPCOM: '18 100, Fido says.'
[2]^ "Visible Earth: The Blue Marble from Apollo 17". NASA. January 31, 2001. Retrieved December 10, 2017.
[3]^ "Apollo 17 30th Anniversary: Antarctica Zoom-out". Scientific Visualization Studio. NASA. November 21, 2002. Retrieved May 11, 2017.
[4]^ Petsko, Gregory A. (April 28, 2011). "The blue marble". Genome Biology. 12 (4): 112. doi:10.1186/gb-2011-12-4-112. PMC 3218853. PMID 21554751.
[5]^ "Apollo 17: The Blue Marble". Ehartwell.com. April 25, 2007. Archived from the original on January 9, 2008. Retrieved January 18, 2008.
(wikipedia source)