¿ 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 November 30 [2]See Explanation. Moving the cursor over the image will bring up an annotated version. Clicking on the image will bring up the highest resolution version available. Cygnus Without Stars Image Credit & Copyright: [3]Bowen James Cameron Explanation: The sky is filled with faintly glowing gas, though it can take a sensitive camera and telescope to see it. For example, this twelve-degree-wide view of the [4]northern part of the constellation [5]Cygnus reveals a complex array of cosmic clouds of gas along the plane of our [6]Milky Way galaxy. The featured mosaic of telescopic images was recorded through two [7]filters: an [8]H-alpha filter that transmits only visible red light from [9]glowing hydrogen atoms, and a blue filter that transmits primarily light emitted by the slight amount of [10]energized oxygen. Therefore, in this 18-hour exposure image, blue areas are [11]hotter than red. Further [12]digital processing has removed the myriad of point-like Milky Way stars from the scene. Recognizable bright nebulas include NGC 7000 ([13]North America Nebula), and IC 5070 ([14]Pelican Nebula) on the left with IC 1318 ([15]Butterfly Nebula) and NGC 6888 ([16]Crescent Nebula) on the right -- but others can be found throughout the wide field. Tomorrow's picture: star forming cluster __________________________________________________________________ [17]< | [18]Archive | [19]Submissions | [20]Index | [21]Search | [22]Calendar | [23]RSS | [24]Education | [25]About APOD | [26]Discuss | [27]> __________________________________________________________________ Authors & editors: [28]Robert Nemiroff ([29]MTU) & [30]Jerry Bonnell ([31]UMCP) NASA Official: Phillip Newman [32]Specific rights apply. [33]NASA Web Privacy Policy and Important Notices A service of: [34]ASD at [35]NASA / [36]GSFC & [37]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2011/CygnusStarless_Cameron_8859.jpg 3. mailto:%20bojaystellar%20@at@%20gmail%20.dot.%20com 4. https://apod.nasa.gov/apod/ap070920.html 5. https://en.wikipedia.org/wiki/Cygnus_(constellation) 6. https://solarsystem.nasa.gov/resources/285/the-milky-way-galaxy/ 7. https://en.wikipedia.org/wiki/Astronomical_filter 8. https://en.wikipedia.org/wiki/H-alpha 9. https://apod.nasa.gov/apod/ap051223.html 10. https://en.wikipedia.org/wiki/Doubly_ionized_oxygen 11. https://www.quora.com/If-blue-is-the-hottest-temperature-then-why-is-red-hot-and-blue-cold-on-taps 12. https://www.snopes.com/tachyon/2009/01/rand.jpg 13. https://apod.nasa.gov/apod/ap081028.html 14. https://apod.nasa.gov/apod/ap161119.html 15. https://apod.nasa.gov/apod/ap180804.html 16. https://apod.nasa.gov/apod/ap201017.html 17. https://apod.nasa.gov/apod/ap201129.html 18. https://apod.nasa.gov/apod/archivepix.html 19. https://apod.nasa.gov/apod/lib/apsubmit2015.html 20. https://apod.nasa.gov/apod/lib/aptree.html 21. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 22. https://apod.nasa.gov/apod/calendar/allyears.html 23. https://apod.nasa.gov/apod.rss 24. https://apod.nasa.gov/apod/lib/edlinks.html 25. https://apod.nasa.gov/apod/lib/about_apod.html 26. http://asterisk.apod.com/discuss_apod.php?date=201130 27. https://apod.nasa.gov/apod/ap201201.html 28. http://www.phy.mtu.edu/faculty/Nemiroff.html 29. http://www.phy.mtu.edu/ 30. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 31. http://www.astro.umd.edu/ 32. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 33. https://www.nasa.gov/about/highlights/HP_Privacy.html 34. https://astrophysics.gsfc.nasa.gov/ 35. https://www.nasa.gov/ 36. https://www.nasa.gov/centers/goddard/ 37. http://www.mtu.edu/