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 July 18 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Shadow and Rainbow Image Credit & [3]License: Dave Loschiavo Explanation: At sunset, an alignment of rainbow and mountain shadow was captured in this remarkable snapshot. The stunning view was recorded from a fire lookout on Smith Peak in the Plumas National Forest near Portola, California on July 13. Still, near sunset it's no accident that the majestic mountain shadow seems to point to the center of the graceful [4]rainbow arc. Due to perspective and the long line of sight the [5]mountain shadow naturally forms a [6]tapering triangular shape, its apex positioned at the point opposite the Sun on the horizon. Following thunderstorms across the region, the [7]rainbow arcs across the early evening sky, with its colorful and characteristic 42 degree arc formed as sunlight is refracted and reflected by the atmospheric water droplets. The geometric center of a rainbow arc lies at the antisolar point. And in this scene from the golden hour on [8]planet Earth, that's also oposite the setting Sun along the distant horizon. Tomorrow's picture: it came from space __________________________________________________________________ [9]< | [10]Archive | [11]Submissions | [12]Index | [13]Search | [14]Calendar | [15]RSS | [16]Education | [17]About APOD | [18]Discuss | [19]> __________________________________________________________________ Authors & editors: [20]Robert Nemiroff ([21]MTU) & Jerry Bonnell ([22]UMCP) NASA Official: Amber Straughn [23]Specific rights apply. [24]NASA Web Privacy, [25]Accessibility, [26]Notices; A service of: [27]ASD at [28]NASA / [29]GSFC, [30]NASA Science Activation & [31]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2607/ShadowandRainbow_Loschiavo.jpg 3. https://creativecommons.org/licenses/by-sa/4.0/deed.en 4. https://apod.nasa.gov/apod/ap230313.html 5. https://apod.nasa.gov/apod/ap200314.html 6. https://apod.nasa.gov/apod/ap161021.html 7. https://www.nesdis.noaa.gov/about/k-12-education/optical-phenomena/what-causes-rainbow 8. https://apod.nasa.gov/apod/ap191011.html 9. https://apod.nasa.gov/apod/ap260717.html 10. https://apod.nasa.gov/apod/archivepix.html 11. https://apod.nasa.gov/apod/lib/apsubmit2015.html 12. https://apod.nasa.gov/apod/lib/aptree.html 13. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 14. https://apod.nasa.gov/apod/calendar/allyears.html 15. https://apod.com/feed.rss 16. https://apod.nasa.gov/apod/lib/edlinks.html 17. https://apod.nasa.gov/apod/lib/about_apod.html 18. https://asterisk.apod.com/discuss_apod.php?date=260718 19. https://apod.nasa.gov/apod/ap260719.html 20. https://www.mtu.edu/physics/department/faculty/nemiroff/ 21. https://www.mtu.edu/physics 22. https://www.astro.umd.edu/ 23. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 24. https://www.nasa.gov/about/highlights/HP_Privacy.html 25. https://www.nasa.gov/general/accessibility/ 26. https://www.nasa.gov/privacy/ 27. https://astrophysics.gsfc.nasa.gov/ 28. https://www.nasa.gov/ 29. https://www.nasa.gov/centers/goddard/ 30. https://science.nasa.gov/learners 31. http://www.mtu.edu/