﻿ 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 October 4 [2]A colorful star field surrounds a big blue reflection nebula. The nebula is elongated across the wide frame and said to resemble the head of folklore-based witch. Please see the explanation for more detailed information. IC 2118: The Witch Head Nebula Image Credit & Copyright: [3]Abdullah Alharbi Explanation: Does this nebula look like the head of a witch? The nebula is [4]known popularly as the Witch Head Nebula because, it is said, the nebula's shape resembles a [5]Halloween-style caricature of a witch's head. Exactly how, though, can be a topic of imaginative speculation. What is clear is that [6]IC 2118 is about 50 [7]light-years across and made of gas and dust that points to -- because it has been partly eroded by -- the nearby star [8]Rigel. One of the brighter stars in the constellation Orion, [9]Rigel lies below the bottom of the [10]featured image. The blue color of the Witch Head Nebula and is caused not only by [11]Rigel's intense blue starlight but because the [12]dust grains scatter blue light more efficiently than red. The same [13]physical process causes Earth's daytime [14]sky to appear blue, although the scatterers in planet [15]Earth's atmosphere are molecules of [16]nitrogen and [17]oxygen. Tomorrow's picture: open space __________________________________________________________________ [18]< | [19]Archive | [20]Submissions | [21]Index | [22]Search | [23]Calendar | [24]RSS | [25]Education | [26]About APOD | [27]Discuss | [28]> __________________________________________________________________ Authors & editors: [29]Robert Nemiroff ([30]MTU) & [31]Jerry Bonnell ([32]UMCP) NASA Official: Phillip Newman [33]Specific rights apply. [34]NASA Web Privacy Policy and Important Notices A service of: [35]ASD at [36]NASA / [37]GSFC, [38]NASA Science Activation & [39]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2310/WitchHead_Alharbi_3051.jpg 3. https://www.instagram.com/a_alharbi97/ 4. https://earthsky.org/todays-image/witch-head-nebula-orion/ 5. https://en.wikipedia.org/wiki/Halloween#/media/File:Halloween_Witch_2011.JPG 6. https://en.wikipedia.org/wiki/IC_2118 7. https://spaceplace.nasa.gov/light-year/ 8. https://en.wikipedia.org/wiki/Rigel 9. https://apod.nasa.gov/apod/ap230407.html 10. https://www.instagram.com/p/CqdsZ47M7xc/ 11. https://apod.nasa.gov/apod/ap220124.html 12. https://curator.jsc.nasa.gov/dust/ 13. http://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html 14. https://spaceplace.nasa.gov/blue-sky/en/ 15. https://www.nasa.gov/image-article/earths-atmospheric-layers-3/ 16. https://www.nasa.gov/solar-system/nasas-curiosity-rover-finds-biologically-useful-nitrogen-on-mars/ 17. https://astrobiology.nasa.gov/news/lightning-oxygen-and-life-detection/ 18. https://apod.nasa.gov/apod/ap231003.html 19. https://apod.nasa.gov/apod/archivepix.html 20. https://apod.nasa.gov/apod/lib/apsubmit2015.html 21. https://apod.nasa.gov/apod/lib/aptree.html 22. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 23. https://apod.nasa.gov/apod/calendar/allyears.html 24. https://apod.nasa.gov/apod.rss 25. https://apod.nasa.gov/apod/lib/edlinks.html 26. https://apod.nasa.gov/apod/lib/about_apod.html 27. https://asterisk.apod.com/discuss_apod.php?date=231004 28. https://apod.nasa.gov/apod/ap231005.html 29. http://www.phy.mtu.edu/faculty/Nemiroff.html 30. http://www.phy.mtu.edu/ 31. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 32. http://www.astro.umd.edu/ 33. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 34. https://www.nasa.gov/about/highlights/HP_Privacy.html 35. https://astrophysics.gsfc.nasa.gov/ 36. https://www.nasa.gov/ 37. https://www.nasa.gov/centers/goddard/ 38. https://science.nasa.gov/learners 39. http://www.mtu.edu/