¿ 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. 2020 September 21 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Omega Sunrise Image Credit & Copyright: [3]Juan Antonio Sendra Explanation: Capturing this sunrise required both luck and timing. First and foremost, precise timing was needed to capture a [4]sailboat crossing right in front of a rising [5]Sun. Additionally, by a lucky coincidence, the background [6]Sun itself appears unusual -- it looks like the [7]Greek letter Omega (W*). In reality, the Sun remained its circular self -- the [8]Omega illusion was created by [9]sunlight refracting through warm air just above the water. Optically, the feet of the capital [10]Omega are actually an [11]inverted image of the Sun region just above it. Although somewhat rare, optical effects caused by the [12]Earth's atmosphere can make distant objects near the horizon -- including the [13]Sun and [14]Moon -- look [15]quite unusual. [16]This single exposure image was taken over the [17]Mediterranean Sea just over two weeks ago near [18]Valencia, [19]Spain. Tomorrow's picture: equal sun arcs __________________________________________________________________ [20]< | [21]Archive | [22]Submissions | [23]Index | [24]Search | [25]Calendar | [26]RSS | [27]Education | [28]About APOD | [29]Discuss | [30]> __________________________________________________________________ Authors & editors: [31]Robert Nemiroff ([32]MTU) & [33]Jerry Bonnell ([34]UMCP) NASA Official: Phillip Newman [35]Specific rights apply. [36]NASA Web Privacy Policy and Important Notices A service of: [37]ASD at [38]NASA / [39]GSFC & [40]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2009/OmegaSunSail_Sendra_8504.jpg 3. https://www.instagram.com/sendratoni/ 4. https://www.wikihow.com/Sail-a-Boat 5. https://solarsystem.nasa.gov/solar-system/sun/overview/ 6. https://solarsystem.nasa.gov/solar-system/sun/in-depth/ 7. https://en.wikipedia.org/wiki/Greek_alphabet 8. https://www.atoptics.co.uk/atoptics/sunmir2.htm 9. https://scienceblogs.com/startswithabang/2013/02/13/the-physics-of-sunsets 10. https://en.wikipedia.org/wiki/Omega 11. https://aty.sdsu.edu/explain/simulations/inf-mir/Omega.html 12. https://spaceplace.nasa.gov/atmosphere/en/ 13. https://apod.nasa.gov/apod/ap120608.html 14. https://apod.nasa.gov/apod/ap090223.html 15. https://apod.nasa.gov/apod/ap191228.html 16. https://www.instagram.com/p/CFCtKxmBSlA/ 17. https://en.wikipedia.org/wiki/Mediterranean_Sea 18. https://youtu.be/NmsFT_OdDlU 19. https://en.wikipedia.org/wiki/Spain 20. https://apod.nasa.gov/apod/ap200920.html 21. https://apod.nasa.gov/apod/archivepix.html 22. https://apod.nasa.gov/apod/lib/apsubmit2015.html 23. https://apod.nasa.gov/apod/lib/aptree.html 24. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 25. https://apod.nasa.gov/apod/calendar/allyears.html 26. https://apod.nasa.gov/apod.rss 27. https://apod.nasa.gov/apod/lib/edlinks.html 28. https://apod.nasa.gov/apod/lib/about_apod.html 29. http://asterisk.apod.com/discuss_apod.php?date=200921 30. https://apod.nasa.gov/apod/ap200922.html 31. http://www.phy.mtu.edu/faculty/Nemiroff.html 32. http://www.phy.mtu.edu/ 33. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 34. http://www.astro.umd.edu/ 35. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 36. https://www.nasa.gov/about/highlights/HP_Privacy.html 37. https://astrophysics.gsfc.nasa.gov/ 38. https://www.nasa.gov/ 39. https://www.nasa.gov/centers/goddard/ 40. http://www.mtu.edu/