¿ 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. 2020 October 14 [2]See Explanation. Clicking on the picture will download the highest resolution version available. The Colorful Clouds of Rho Ophiuchi Image Credit & Copyright: [3]Amir H. Abolfath Explanation: The many spectacular colors of the [4]Rho Ophiuchi (oh'-fee-yu-kee) clouds highlight the many processes that occur there. The blue regions shine primarily by reflected light. Blue light from the [5]Rho Ophiuchi star system and nearby stars [6]reflects more efficiently off this portion of the nebula than red light. The Earth's [7]daytime sky appears blue for the same reason. The red and yellow regions shine primarily because of [8]emission from the nebula's atomic and molecular gas. Light from nearby blue stars - more energetic than the bright star [9]Antares - knocks [10]electrons away from the gas, which then shines when the electrons recombine with the gas. The [11]dark brown regions are caused by [12]dust grains - born in young stellar atmospheres - which effectively block light emitted behind them. The [13]Rho Ophiuchi star clouds, well in front of the [14]globular [15]cluster [16]M4 visible [17]here on the upper right, are even more colorful than [18]humans can see - the clouds emits light in every [19]wavelength band from the [20]radio to the [21]gamma-ray. Astrophysicists: [22]Browse 2,200+ codes in the Astrophysics Source Code Library Tomorrow's picture: open space __________________________________________________________________ [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/2010/RhoAntares_Abolfath_3000.jpg 3. http://amir.torgheh.ir/ 4. https://en.wikipedia.org/wiki/Rho_Ophiuchi_cloud_complex 5. https://en.wikipedia.org/wiki/Rho_Ophiuchi 6. https://apod.nasa.gov/apod/reflection_nebulae.html 7. https://spaceplace.nasa.gov/blue-sky/en/ 8. https://apod.nasa.gov/apod/emission_nebulae.html 9. https://en.wikipedia.org/wiki/Antares 10. http://www-istp.gsfc.nasa.gov/Education/welect.html 11. https://apod.nasa.gov/apod/ap030202.html 12. http://nedwww.ipac.caltech.edu/level5/Mathis/Mathis1.html 13. https://apod.nasa.gov/apod/ap200516.html 14. http://messier.seds.org/glob.html 15. https://www.youtube.com/watch?v=cxtdIfdXP9s 16. https://apod.nasa.gov/apod/ap000523.html 17. http://amir.torgheh.ir/picture.php?/1228/category/13 18. https://www.colormatters.com/color-and-vision/color-and-vision-matters 19. https://science.nasa.gov/ems/01_intro 20. https://science.nasa.gov/ems/05_radiowaves 21. https://science.nasa.gov/ems/12_gammarays 22. http://ascl.net/ 23. https://apod.nasa.gov/apod/ap201013.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=201014 33. https://apod.nasa.gov/apod/ap201015.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/