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 June 19 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Northern Summer Twilight Image Credit & [3]Copyright: [4]Justin Anderson Explanation: [5]Nights grow shorter and [6]days grow longer as the summer solstice approaches in the north. Usually seen at high latitudes in summer months, noctilucent or night shining clouds begin to make their appearance. [7]Drifting near the [8]edge of space about 80 kilometers above the Earth's surface, these icy clouds were still reflecting the sunlight on June 14. Though the Sun was [9]below the horizon as seen north of Forrest, Manitoba, Canada, they were caught in a single exposure of a near midnight twilight sky. Multiple exposures of the foreground track the lower altitude flash of fireflies, another fleeting apparition [10]shining in the summer night. Tomorrow's picture: the season's sunrise __________________________________________________________________ [11]< | [12]Archive | [13]Submissions | [14]Index | [15]Search | [16]Calendar | [17]RSS | [18]Education | [19]About APOD | [20]Discuss | [21]> __________________________________________________________________ Authors & editors: [22]Robert Nemiroff ([23]MTU) & [24]Jerry Bonnell ([25]UMCP) NASA Official: Phillip Newman [26]Specific rights apply. [27]NASA Web Privacy Policy and Important Notices A service of: [28]ASD at [29]NASA / [30]GSFC & [31]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2106/IMG_1088_resize.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. https://www.facebook.com/AuroraJustinAnderson 5. https://apod.nasa.gov/apod/ap191221.html 6. https://apod.nasa.gov/apod/ap190627.html 7. https://www.nasa.gov/feature/goddard/2018/nasa-balloon-mission-captures-electric-blue-clouds 8. https://www.nasa.gov/mission_pages/aim/edge_of_space.html 9. https://apod.nasa.gov/apod/ap210605.html 10. https://apod.nasa.gov/apod/ap110805.html 11. https://apod.nasa.gov/apod/ap210618.html 12. https://apod.nasa.gov/apod/archivepix.html 13. https://apod.nasa.gov/apod/lib/apsubmit2015.html 14. https://apod.nasa.gov/apod/lib/aptree.html 15. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 16. https://apod.nasa.gov/apod/calendar/allyears.html 17. https://apod.nasa.gov/apod.rss 18. https://apod.nasa.gov/apod/lib/edlinks.html 19. https://apod.nasa.gov/apod/lib/about_apod.html 20. http://asterisk.apod.com/discuss_apod.php?date=210619 21. https://apod.nasa.gov/apod/ap210620.html 22. http://www.phy.mtu.edu/faculty/Nemiroff.html 23. http://www.phy.mtu.edu/ 24. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 25. http://www.astro.umd.edu/ 26. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 27. https://www.nasa.gov/about/highlights/HP_Privacy.html 28. https://astrophysics.gsfc.nasa.gov/ 29. https://www.nasa.gov/ 30. https://www.nasa.gov/centers/goddard/ 31. http://www.mtu.edu/