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 November 3 [2]The picture shows a deep image of the part of the Orion Nebula that features both the Horsehead Nebula and the Flame Nebula. Detailed surrounding dust and stars are also visible. Please see the explanation for more detailed information. The Horsehead and Flame Nebulas Image Credit & Copyright: [3]Wissam Ayoub Explanation: The [4]Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the orange [5]emission nebula at the far right of the [6]featured picture. The [7]horse-head feature is dark because it is really an opaque [8]dust cloud that lies in front of the bright [9]emission nebula. Like clouds in [10]Earth's atmosphere, this cosmic cloud has assumed a [11]recognizable shape by chance. After [12]many thousands of years, the internal motions of the cloud will surely alter its appearance. The emission [13]nebula's orange color is caused by [14]electrons recombining with [15]protons to form [16]hydrogen atoms. Toward the lower left of the image is the [17]Flame Nebula, an orange-tinged nebula that also contains intricate filaments of dark dust. Two prominent [18]reflection nebulas are visible: round [19]IC 432 on the far left, and [20]blue [21]NGC 2023 just to the lower left of the Horsehead nebula. Each glows primarily by [22]reflecting the light of their central star. Discovery + Outreach: [23]Graduate student research position open for APOD Tomorrow's picture: open space __________________________________________________________________ [24]< | [25]Archive | [26]Submissions | [27]Index | [28]Search | [29]Calendar | [30]RSS | [31]Education | [32]About APOD | [33]Discuss | [34]> __________________________________________________________________ Authors & editors: [35]Robert Nemiroff ([36]MTU) & [37]Jerry Bonnell ([38]UMCP) NASA Official: Phillip Newman [39]Specific rights apply. [40]NASA Web Privacy Policy and Important Notices A service of: [41]ASD at [42]NASA / [43]GSFC & [44]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2111/HorseFlame_Ayoub_4305.jpg 3. https://www.astrobin.com/users/Wissam_Astrophotography/ 4. https://en.wikipedia.org/wiki/Horsehead_nebula 5. https://apod.nasa.gov/apod/emission_nebulae.html 6. https://www.astrobin.com/biwuli/0/ 7. https://apod.nasa.gov/apod/ap140728.html 8. https://apod.nasa.gov/apod/ap030706.html 9. https://en.wikipedia.org/wiki/Emission_nebula 10. http://www.nasa.gov/mission_pages/sunearth/science/atmosphere-layers2.html 11. http://www.brucevanpatter.com/cloudshapes.html 12. https://cdn.shopify.com/s/files/1/0272/4770/6214/articles/do-cats-get-bored-800x533.jpg 13. https://apod.nasa.gov/apod/ap061015.html 14. https://history.aip.org/exhibits/electron/ 15. https://home.cern/news/news/physics/proton-century 16. https://periodic.lanl.gov/1.shtml 17. https://apod.nasa.gov/apod/ap210412.html 18. https://apod.nasa.gov/apod/reflection_nebulae.html 19. https://telescopius.com/deep-sky/object/606/ic-432/bright-nebula 20. https://spaceplace.nasa.gov/blue-sky/en/ 21. https://apod.nasa.gov/apod/ap180329.html 22. https://apod.nasa.gov/apod/ap070611.html 23. https://asterisk.apod.com/viewtopic.php?f=28&t=41989 24. https://apod.nasa.gov/apod/ap211102.html 25. https://apod.nasa.gov/apod/archivepix.html 26. https://apod.nasa.gov/apod/lib/apsubmit2015.html 27. https://apod.nasa.gov/apod/lib/aptree.html 28. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 29. https://apod.nasa.gov/apod/calendar/allyears.html 30. https://apod.nasa.gov/apod.rss 31. https://apod.nasa.gov/apod/lib/edlinks.html 32. https://apod.nasa.gov/apod/lib/about_apod.html 33. http://asterisk.apod.com/discuss_apod.php?date=211103 34. https://apod.nasa.gov/apod/ap211104.html 35. http://www.phy.mtu.edu/faculty/Nemiroff.html 36. http://www.phy.mtu.edu/ 37. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 38. http://www.astro.umd.edu/ 39. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 40. https://www.nasa.gov/about/highlights/HP_Privacy.html 41. https://astrophysics.gsfc.nasa.gov/ 42. https://www.nasa.gov/ 43. https://www.nasa.gov/centers/goddard/ 44. http://www.mtu.edu/