¿ 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 September 28 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Filaments of the Cygnus Loop Image Credit: [3]ESA/[4]Hubble & [5]NASA, [6]W. Blair; Acknowledgement: [7]Leo Shatz Explanation: What lies at the edge of an expanding supernova? Subtle and delicate in appearance, these ribbons of shocked interstellar gas are part of a blast wave at the expanding edge of a violent [8]stellar explosion that would have been easily visible to humans during the [9]late stone age, about 20,000 years ago. The [10]featured image was recorded by the [11]Hubble Space Telescope and is a closeup of the outer edge of a supernova remnant known as the Cygnus Loop or [12]Veil Nebula. The filamentary shock front is [13]moving toward the top of the frame at about 170 kilometers per second, while glowing in light emitted by atoms of excited [14]hydrogen gas. The distances to stars thought to be interacting with the [15]Cygnus Loop have recently been found by the Gaia mission to be about 2400 light years distant. The whole [16]Cygnus Loop spans six [17]full Moons across the sky, corresponding to about 130 [18]light years, and parts can be seen with a small telescope toward the [19]constellation of the [20]Swan (Cygnus). Tomorrow's picture: tilted planets __________________________________________________________________ [21]< | [22]Archive | [23]Submissions | [24]Index | [25]Search | [26]Calendar | [27]RSS | [28]Education | [29]About APOD | [30]Discuss | [31]> __________________________________________________________________ Authors & editors: [32]Robert Nemiroff ([33]MTU) & [34]Jerry Bonnell ([35]UMCP) NASA Official: Phillip Newman [36]Specific rights apply. [37]NASA Web Privacy Policy and Important Notices A service of: [38]ASD at [39]NASA / [40]GSFC & [41]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2009/CygnusFilament_HubbleShatz_1472.jpg 3. https://www.esa.int/ 4. https://www.spacetelescope.org/ 5. https://www.nasa.gov/ 6. https://physics-astronomy.jhu.edu/directory/william-blair/ 7. https://www.astrobin.com/users/spinlock/ 8. https://youtu.be/aysiMbgml5g 9. https://en.wikipedia.org/wiki/Timeline_of_human_prehistory#Upper_Paleolithic 10. https://www.spacetelescope.org/images/potw2034a/ 11. https://www.nasa.gov/mission_pages/hubble/main/index.html 12. https://apod.nasa.gov/apod/ap191031.html 13. https://www.astrobin.com/4kxgvn/ 14. https://periodic.lanl.gov/1.shtml 15. https://en.wikipedia.org/wiki/Cygnus_Loop 16. https://apod.nasa.gov/apod/ap200826.html 17. https://apod.nasa.gov/apod/ap160201.html 18. https://spaceplace.nasa.gov/light-year/en/ 19. https://en.wikipedia.org/wiki/Cygnus_(constellation) 20. https://en.wikipedia.org/wiki/Swan#/media/File:Cygnus_olor_2_(Marek_Szczepanek).jpg 21. https://apod.nasa.gov/apod/ap200927.html 22. https://apod.nasa.gov/apod/archivepix.html 23. https://apod.nasa.gov/apod/lib/apsubmit2015.html 24. https://apod.nasa.gov/apod/lib/aptree.html 25. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 26. https://apod.nasa.gov/apod/calendar/allyears.html 27. https://apod.nasa.gov/apod.rss 28. https://apod.nasa.gov/apod/lib/edlinks.html 29. https://apod.nasa.gov/apod/lib/about_apod.html 30. http://asterisk.apod.com/discuss_apod.php?date=200928 31. https://apod.nasa.gov/apod/ap200929.html 32. http://www.phy.mtu.edu/faculty/Nemiroff.html 33. http://www.phy.mtu.edu/ 34. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 35. http://www.astro.umd.edu/ 36. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 37. https://www.nasa.gov/about/highlights/HP_Privacy.html 38. https://astrophysics.gsfc.nasa.gov/ 39. https://www.nasa.gov/ 40. https://www.nasa.gov/centers/goddard/ 41. http://www.mtu.edu/