﻿ 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. 2022 September 18 [2]The featured image the Sun in many positions above the Callanish stones. Please see the explanation for more detailed information. Analemma over the Callanish Stones Image Credit & Copyright: [3]Giuseppe Petricca Explanation: If you went outside at the same time every day and took a picture that included the Sun, how would the Sun's position change? A more visual answer to that question is an [4]analemma, a composite image taken from the same spot at the same time over the course of a year. The [5]featured analemma was composed from images taken every few days at noon near the village of [6]Callanish in the [7]Outer Hebrides in [8]Scotland, [9]UK. In the foreground are the [10]Callanish [11]Stones, a stone circle built around 2700 BC during humanity's [12]Bronze Age. It is not known if the placement of the [13]Callanish Stones has or had astronomical significance. The ultimate causes for the [14]figure-8 shape of this and all analemmas are the [15]tilt of the Earth axis and the [16]ellipticity of the [17]Earth's orbit around the [18]Sun. At the [19]solstices, the Sun will appear at the top or bottom of an analemma. The featured image was taken near the December solstice and so the Sun appears near the bottom. [20]Equinoxes, however, correspond to analemma middle points -- not the intersection point. This coming Friday at 1:04 am ([21]UT) -- Thursday in the [22]Americas -- is the [23]equinox ("equal night"), when day and night are equal over all of planet Earth. Many [24]cultures celebrate a change of season at an [25]equinox. Explore Your Universe: [26]Random APOD Generator Tomorrow's picture: lightning layer __________________________________________________________________ [27]< | [28]Archive | [29]Submissions | [30]Index | [31]Search | [32]Calendar | [33]RSS | [34]Education | [35]About APOD | [36]Discuss | [37]> __________________________________________________________________ Authors & editors: [38]Robert Nemiroff ([39]MTU) & [40]Jerry Bonnell ([41]UMCP) NASA Official: Phillip Newman [42]Specific rights apply. [43]NASA Web Privacy Policy and Important Notices A service of: [44]ASD at [45]NASA / [46]GSFC, [47]NASA Science Activation & [48]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2209/CallanishAnalemma_Petricca_1280.jpg 3. https://www.astrobin.com/users/gmrphotographer/ 4. https://en.wikipedia.org/wiki/Analemma 5. https://gmrphotographer.net/wordpress/2019/01/29/2017-solar-analemma-over-callanish/ 6. https://en.wikipedia.org/wiki/Callanish 7. https://en.wikipedia.org/wiki/Outer_Hebrides 8. https://en.wikipedia.org/wiki/Scotland 9. https://en.wikipedia.org/wiki/United_Kingdom 10. https://en.wikipedia.org/wiki/Callanish_Stones 11. https://youtu.be/5mcPHxuVhWk 12. https://en.wikipedia.org/wiki/Bronze_Age 13. https://www.youtube.com/watch?v=mkbEhp8hJN8 14. https://apod.nasa.gov/apod/ap160822.html 15. https://spaceplace.nasa.gov/seasons/en/ 16. https://mathworld.wolfram.com/Ellipse.html 17. http://bhenvis.nic.in/images/season_climate.jpg 18. https://solarsystem.nasa.gov/solar-system/sun/exploration/ 19. https://apod.nasa.gov/apod/ap170621.html 20. https://apod.nasa.gov/apod/ap170319.html 21. https://eclipse.gsfc.nasa.gov/SEhelp/TimeZone.html 22. https://en.wikipedia.org/wiki/Americas 23. https://en.wikipedia.org/wiki/Equinox 24. http://mentalfloss.com/article/59049/autumnal-equinox-traditions 25. https://apod.nasa.gov/apod/ap160320.html 26. http://apod.nasa.gov/apod/random_apod.html 27. https://apod.nasa.gov/apod/ap220917.html 28. https://apod.nasa.gov/apod/archivepix.html 29. https://apod.nasa.gov/apod/lib/apsubmit2015.html 30. https://apod.nasa.gov/apod/lib/aptree.html 31. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 32. https://apod.nasa.gov/apod/calendar/allyears.html 33. https://apod.nasa.gov/apod.rss 34. https://apod.nasa.gov/apod/lib/edlinks.html 35. https://apod.nasa.gov/apod/lib/about_apod.html 36. http://asterisk.apod.com/discuss_apod.php?date=220918 37. https://apod.nasa.gov/apod/ap220919.html 38. http://www.phy.mtu.edu/faculty/Nemiroff.html 39. http://www.phy.mtu.edu/ 40. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 41. http://www.astro.umd.edu/ 42. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 43. https://www.nasa.gov/about/highlights/HP_Privacy.html 44. https://astrophysics.gsfc.nasa.gov/ 45. https://www.nasa.gov/ 46. https://www.nasa.gov/centers/goddard/ 47. https://science.nasa.gov/learners 48. http://www.mtu.edu/