Astronomy Picture of the Day [1]Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2021 April 29 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Apollo 17: The Crescent Earth Image Credit: [3]Apollo 17, [4]NASA; Restoration - [5]Toby Ord Explanation: [6]Our fair planet sports a curved, sunlit crescent against the black backdrop of space in this stunning photograph. From the unfamiliar perspective, [7]the Earth is small and, like a [8]telescopic image of a distant planet, the entire horizon is completely within the field of view. Enjoyed by [9]crews on board the International Space Station, only much closer views of the planet are possible from low Earth orbit. Orbiting the planet once every 90 minutes, a spectacle of clouds, oceans, and continents [10]scrolls beneath them with the partial arc of the planet's edge in the distance. [11]But this digitally restored image presents a view so far only achieved by 24 humans, [12]Apollo astronauts who traveled to the Moon and back again between 1968 and 1972. The original photograph, AS17-152-23420, was taken by the homeward bound crew of Apollo 17, on December 17, 1972. For now it's the last picture of Earth from this planetary perspective taken by [13]human hands. - [14]NASA Remembers Michael Collins - Tomorrow's picture: pixels in space __________________________________________________________________ [15]< | [16]Archive | [17]Submissions | [18]Index | [19]Search | [20]Calendar | [21]RSS | [22]Education | [23]About APOD | [24]Discuss | [25]> __________________________________________________________________ Authors & editors: [26]Robert Nemiroff ([27]MTU) & [28]Jerry Bonnell ([29]UMCP) NASA Official: Phillip Newman [30]Specific rights apply. [31]NASA Web Privacy Policy and Important Notices A service of: [32]ASD at [33]NASA / [34]GSFC & [35]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2104/AS17-152-23420_Ord.jpg 3. https://www-pao.ksc.nasa.gov/history/apollo/apollo-17/apollo-17.htm 4. https://www.nasa.gov/home/index.html 5. http://www.tobyord.com/earth 6. https://www.nasa.gov/topics/earth/index.html 7. https://www.youtube.com/watch?v=57CDqSh5HXc 8. https://apod.nasa.gov/apod/ap180728.html 9. https://www.nasa.gov/mission_pages/station/main/index.html 10. https://apod.nasa.gov/apod/ap210423.html 11. http://www.tobyord.com/earth 12. https://solarsystem.nasa.gov/news/890/who-has-walked-on-the-moon/ 13. https://eol.jsc.nasa.gov/SearchPhotos/photo.pl?mission=AS17&roll=152&frame=23420 14. https://www.nasa.gov/michael-collins 15. https://apod.nasa.gov/apod/ap210428.html 16. https://apod.nasa.gov/apod/archivepix.html 17. https://apod.nasa.gov/apod/lib/apsubmit2015.html 18. https://apod.nasa.gov/apod/lib/aptree.html 19. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 20. https://apod.nasa.gov/apod/calendar/allyears.html 21. https://apod.nasa.gov/apod.rss 22. https://apod.nasa.gov/apod/lib/edlinks.html 23. https://apod.nasa.gov/apod/lib/about_apod.html 24. http://asterisk.apod.com/discuss_apod.php?date=210429 25. https://apod.nasa.gov/apod/ap210430.html 26. http://www.phy.mtu.edu/faculty/Nemiroff.html 27. http://www.phy.mtu.edu/ 28. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 29. http://www.astro.umd.edu/ 30. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 31. https://www.nasa.gov/about/highlights/HP_Privacy.html 32. https://astrophysics.gsfc.nasa.gov/ 33. https://www.nasa.gov/ 34. https://www.nasa.gov/centers/goddard/ 35. http://www.mtu.edu/