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. 2024 January 13 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Circling the Sun Image Credit & [3]Copyright: [4]Radoslav Zboran Explanation: [5]Earth's orbit around the Sun is not a circle, it's an ellipse. The point along its elliptical orbit where our fair planet is [6]closest to the Sun is called perihelion. This year, perihelion was on January 2 at 01:00 UTC, with the Earth about 3 million [7]miles closer to the Sun than it was at aphelion (last July 6), the farthest point in its elliptical orbit. Of course, distance from the Sun [8]doesn't determine the seasons, and it doesn't the determine size of Sun halos. [9]Easier to see with the Sun hidden behind a tall tree trunk, this beautiful ice halo forms a 22 degree-wide circle around the Sun, recorded while strolling through the countryside near Heroldstatt, Germany. The Sun halo's 22 degree angular diameter is [10]determined by the six-sided geometry of water ice crystals drifting high in planet Earth's atmosphere. Tomorrow's picture: there be dragons __________________________________________________________________ [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: Ryan Smallcomb [26]Specific rights apply. [27]NASA Web Privacy Policy and Important Notices A service of: [28]ASD at [29]NASA / [30]GSFC, [31]NASA Science Activation & [32]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2401/22halo_Zboran.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. https://www.instagram.com/zboran.r/?igsh=YTQwZjQ0NmI0OA== 5. https://earthsky.org/tonight/earth-comes-closest-to-sun-every-year-in-early-january/ 6. https://blogs.nasa.gov/parkersolarprobe/2024/01/08/nasas-parker-solar-probe-completes-18th-close-approach-to-the-sun/ 7. https://apod.nasa.gov/apod/ap201003.html 8. https://earthsky.org/astronomy-essentials/december-solstice-january-perihelion-related/ 9. https://apod.nasa.gov/apod/ap231014.html 10. https://atoptics.co.uk/blog/22-halo-formation/ 11. https://apod.nasa.gov/apod/ap240112.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=240113 21. https://apod.nasa.gov/apod/ap240114.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. https://science.nasa.gov/learners 32. http://www.mtu.edu/