¿ 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. 2021 April 12 [2]A picture of the center of the Flame Nebula is shown, with the bright star Alnitak off on the left. For more details, please read the explanation. Alnitak and the Flame Nebula Image Credit & Copyright: [3]Team ARO Explanation: What lights up the Flame Nebula? Fifteen hundred light years away towards the [4]constellation of [5]Orion lies a nebula which, from its glow and dark [6]dust lanes, appears, on the left, like a billowing fire. But [7]fire, the rapid acquisition of [8]oxygen, is not what makes this [9]Flame glow. Rather the bright star [10]Alnitak, the easternmost star in the [11]Belt of Orion visible on the far left, shines energetic light into the [12]Flame that knocks electrons away from the great clouds of [13]hydrogen gas that reside there. Much of the glow results when the [14]electrons and ionized hydrogen recombine. The [15]featured picture of the Flame Nebula (NGC 2024) was taken across three [16]visible color [17]bands with detail added by a [18]long duration exposure taken in [19]light emitted only by hydrogen. The [20]Flame Nebula is part of the [21]Orion Molecular Cloud Complex, a star-forming region that includes the famous [22]Horsehead Nebula. Tomorrow's picture: a suprising wobble __________________________________________________________________ [23]< | [24]Archive | [25]Submissions | [26]Index | [27]Search | [28]Calendar | [29]RSS | [30]Education | [31]About APOD | [32]Discuss | [33]> __________________________________________________________________ Authors & editors: [34]Robert Nemiroff ([35]MTU) & [36]Jerry Bonnell ([37]UMCP) NASA Official: Phillip Newman [38]Specific rights apply. [39]NASA Web Privacy Policy and Important Notices A service of: [40]ASD at [41]NASA / [42]GSFC & [43]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2104/Flame_ARO_1462.jpg 3. http://astroaro.fr/en/home/ 4. https://spaceplace.nasa.gov/constellations/en/ 5. https://apod.nasa.gov/apod/ap200329.html 6. https://apod.nasa.gov/apod/ap990509.html 7. https://en.wikipedia.org/wiki/Fire 8. https://periodic.lanl.gov/8.shtml 9. http://en.wikipedia.org/wiki/NGC_2024 10. https://apod.nasa.gov/apod/ap061229.html 11. https://apod.nasa.gov/apod/ap090929.html 12. https://ui.adsabs.harvard.edu/abs/1997IAUS..182P..18M/abstract 13. https://youtu.be/Szv30aUEsxM 14. https://www.aip.org/history/electron/ 15. https://astroaro.fr/en/en_neb-de-la-flamme/ 16. https://science.nasa.gov/ems/09_visiblelight 17. https://en.wikipedia.org/wiki/Photometric_system 18. https://i.kym-cdn.com/photos/images/newsfeed/000/002/110/longcat.jpg 19. http://www.astronomyknowhow.com/hydrogen-alpha.htm 20. https://apod.nasa.gov/apod/ap191102.html 21. https://youtu.be/07dve0EnUX8 22. https://apod.nasa.gov/apod/ap200412.html 23. https://apod.nasa.gov/apod/ap210411.html 24. https://apod.nasa.gov/apod/archivepix.html 25. https://apod.nasa.gov/apod/lib/apsubmit2015.html 26. https://apod.nasa.gov/apod/lib/aptree.html 27. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 28. https://apod.nasa.gov/apod/calendar/allyears.html 29. https://apod.nasa.gov/apod.rss 30. https://apod.nasa.gov/apod/lib/edlinks.html 31. https://apod.nasa.gov/apod/lib/about_apod.html 32. http://asterisk.apod.com/discuss_apod.php?date=210412 33. https://apod.nasa.gov/apod/ap210413.html 34. http://www.phy.mtu.edu/faculty/Nemiroff.html 35. http://www.phy.mtu.edu/ 36. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 37. http://www.astro.umd.edu/ 38. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 39. https://www.nasa.gov/about/highlights/HP_Privacy.html 40. https://astrophysics.gsfc.nasa.gov/ 41. https://www.nasa.gov/ 42. https://www.nasa.gov/centers/goddard/ 43. http://www.mtu.edu/