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. 2023 December 18 [2]A checkerboard is shown with squares colored light and dark grey. A green tube sits on the board and casts a shadow. The image has a letter A typed on a dark square, and a letter B types on a light square cast in shadow. The question is asked if the two squares, A and B, are really the same color. Please see the explanation for more detailed information. The Same Color Illusion Image Credit: [3]Edward H. Adelson, [4]Wikipedia Explanation: Are squares A and B the same color? They are! To verify this, either run your cursor over the image or click [5]here to see them connected. The [6]featured illusion, an example of the [7]same color illusion, illustrates that purely human perceptions in science may be [8]ambiguous or inaccurate, even such a seemingly direct [9]perception as relative color. Similar [10]illusions exist on the [11]sky, such as the [12]size of the Moon near the horizon, or the [13]apparent shapes of astronomical objects. The advent of automated, reproducible measuring devices such as [14]CCDs have made [15]science in general and [16]astronomy in particular less prone to, but not free of, [17]human-biased [18]illusions. APOD Year in Review (2023): [19]RJN's Night Sky Network Lecture Tomorrow's picture: california on high __________________________________________________________________ [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]NASA Science Activation & [41]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2312/greyilliusion_wikipedia_960.jpg 3. https://bcs.mit.edu/directory/edward-adelson 4. https://en.wikipedia.org/wiki/Image:Same_color_illusion.png 5. https://apod.nasa.gov/apod/image/0707/samecolor_wikipedia_connected.jpg 6. https://michaelbach.de/ot/lum-adelsonCheckShadow/ 7. https://en.wikipedia.org/wiki/Same_color_illusion 8. https://www.quora.com/Optical-Illusions/What-are-some-great-optical-illusions 9. https://www.youtube.com/watch?v=y8U0YPHxiFQ 10. https://apod.nasa.gov/apod/ap121003.html 11. https://www.facebook.com/APOD.Sky 12. https://apod.nasa.gov/apod/ap090616.html 13. https://apod.nasa.gov/apod/ap190211.html 14. https://en.wikipedia.org/wiki/Charge-coupled_device 15. https://science.nasa.gov/ 16. https://www.iau.org/public/themes/astronomy_in_everyday_life/ 17. https://www.youtube.com/watch?v=w8Zz05t19dg 18. https://www.michaelbach.de/ot/ 19. https://www.youtube.com/watch?v=S00SNpSNKZo 20. https://apod.nasa.gov/apod/ap231217.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.com/feed.rss 27. https://apod.nasa.gov/apod/lib/edlinks.html 28. https://apod.nasa.gov/apod/lib/about_apod.html 29. https://asterisk.apod.com/discuss_apod.php?date=231218 30. https://apod.nasa.gov/apod/ap231219.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. https://science.nasa.gov/learners 41. http://www.mtu.edu/