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. 2026 April 21 [2]A starry sky is seen above snowy mountains. In the sky three arches are visible, with the Milky Way on either side and zodiacal light in the center. Please see the explanation for more detailed information. Three Sky Arches over Snowy Alps Image Credit & Copyright: [3]Angel Fux Explanation: Why are there three arches across the sky instead of two? Last month, after being [4]dropped off by a helicopter at a [5]high mountain peak in the [6]Alps near the [7]Swiss [8]Italian border, an adventurous astrophotographer expected two arches of [9]our Milky Way galaxy to be [10]visible during the night. These were the inner arch looking in [11]toward the center of our galaxy on the left, visible just before sunrise, and the [12]outer arch on the right visible just after sunset. But there were three arches. The [13]surprised [14]astrophotographer soon realized that the sky was [15]so dark that an [16]entire arc of faint [17]zodiacal light was also noticeable -- sunlight scattered by inner [18]Solar System dust. And it artfully connected the two Milky Way arches! The next morning a helicopter picked the astrophotographer back up, and after 40 hours of processing and combining that night's images, the [19]featured triple-arch 360-degree panorama resulted. Jigsaw Vistas: [20]Astronomy Puzzle of the Day Tomorrow's picture: open space __________________________________________________________________ [21]< | [22]Archive | [23]Submissions | [24]Index | [25]Search | [26]Calendar | [27]RSS | [28]Education | [29]About APOD | [30]Discuss | [31]> __________________________________________________________________ Authors & editors: [32]Robert Nemiroff ([33]MTU) & [34]Jerry Bonnell ([35]UMCP) NASA Official: Amber Straughn [36]Specific rights apply. [37]NASA Web Privacy, [38]Accessibility, [39]Notices; A service of: [40]ASD at [41]NASA / [42]GSFC, [43]NASA Science Activation & [44]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2604/TripleArchAlps_Fux_7500.jpg 3. https://www.instagram.com/angelfux 4. https://blog.angelfux.com/p/triple-arch-at-4200m-matterhorn 5. https://youtu.be/rxeK5Q2N-Is?t=617 6. https://en.wikipedia.org/wiki/Alps 7. https://en.wikipedia.org/wiki/Switzerland 8. https://en.wikipedia.org/wiki/Italy 9. https://science.nasa.gov/asset/webb/milky-way-and-our-location/ 10. https://capturetheatlas.com/best-time-to-see-the-milky-way/ 11. https://apod.nasa.gov/apod/ap251109.html 12. https://apod.nasa.gov/apod/ap220312.html 13. https://www.reddit.com/r/aww/comments/2jqsdk/the_omg_cat/#lightbox 14. https://www.levoyageur.ch/women-invited/angel-fux 15. https://apod.nasa.gov/apod/ap200408.html 16. https://apod.nasa.gov/apod/ap170429.html 17. https://en.wikipedia.org/wiki/Zodiacal_light 18. https://eyes.nasa.gov/apps/solar-system/#/home 19. https://www.instagram.com/p/DWbq_YKjW0X/ 20. https://www.scigames.org/apps/webjigsaw2/index.php 21. https://apod.nasa.gov/apod/ap260420.html 22. https://apod.nasa.gov/apod/archivepix.html 23. https://apod.nasa.gov/apod/lib/apsubmit2015.html 24. https://apod.nasa.gov/apod/lib/aptree.html 25. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 26. https://apod.nasa.gov/apod/calendar/allyears.html 27. https://apod.com/feed.rss 28. https://apod.nasa.gov/apod/lib/edlinks.html 29. https://apod.nasa.gov/apod/lib/about_apod.html 30. https://asterisk.apod.com/discuss_apod.php?date=260421 31. https://apod.nasa.gov/apod/ap260422.html 32. http://www.phy.mtu.edu/faculty/Nemiroff.html 33. http://www.phy.mtu.edu/ 34. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 35. http://www.astro.umd.edu/ 36. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 37. https://www.nasa.gov/about/highlights/HP_Privacy.html 38. https://www.nasa.gov/general/accessibility/ 39. https://www.nasa.gov/privacy/ 40. https://astrophysics.gsfc.nasa.gov/ 41. https://www.nasa.gov/ 42. https://www.nasa.gov/centers/goddard/ 43. https://science.nasa.gov/learners 44. http://www.mtu.edu/