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. 2019 August 29 [2]See Explanation. Clicking on the picture will download the highest resolution version available. M27: Not a Comet Image Credit & [3]Copyright: [4]Bob Franke Explanation: While hunting for comets in the skies above 18th century France, [5]astronomer Charles Messier diligently kept a list of the things he encountered that were definitely not comets. This is number 27 on his [6]now famous not-a-comet list. In fact, 21st century astronomers would identify it as a [7]planetary nebula, but it's not a planet either, even though it may [8]appear round and planet-like in a small telescope. Messier 27 (M27) is an excellent example of a gaseous emission nebula created as a [9]sun-like star runs out of nuclear fuel in its core. The nebula forms as the star's outer layers are expelled into space, with a visible glow generated by atoms excited by the dying star's intense but invisible [10]ultraviolet light. Known by the popular name of the [11]Dumbbell Nebula, the beautifully symmetric interstellar gas cloud is over 2.5 light-years across and about 1,200 light-years away in the [12]constellation Vulpecula. This impressive color composite highlights details within the well-studied central region and fainter, seldom imaged features in the nebula's [13]outer halo. It incorporates broad and narrowband [14]images recorded using filters sensitive to emission from hydrogen and oxygen atoms. Tomorrow's picture: pixels in space __________________________________________________________________ [15]< | [16]Archive | [17]Submissions | [18]Index | [19]Search | [20]Calendar | [21]RSS | [22]Education | [23]About APOD | [24]Discuss | [25]> __________________________________________________________________ Authors & editors: [26]Robert Nemiroff ([27]MTU) & [28]Jerry Bonnell ([29]UMCP) NASA Official: Phillip Newman [30]Specific rights apply. [31]NASA Web Privacy Policy and Important Notices A service of: [32]ASD at [33]NASA / [34]GSFC & [35]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/1908/m27bigFranke.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. http://bf-astro.com/ 5. http://messier.seds.org/xtra/history/biograph.html 6. http://messier.seds.org/xtra/history/m-cat.html 7. http://messier.seds.org/planetar.html 8. https://apod.nasa.gov/apod/ap030614.html 9. https://apod.nasa.gov/apod/ap100221.html 10. http://imagine.gsfc.nasa.gov/science/toolbox/emspectrum1.html 11. http://messier.seds.org/m/m027.html 12. http://hawastsoc.org/deepsky/vul/index.html 13. https://apod.nasa.gov/apod/ap100509.html 14. http://bf-astro.com/m27/m27.htm 15. https://apod.nasa.gov/apod/ap190828.html 16. https://apod.nasa.gov/apod/archivepix.html 17. https://apod.nasa.gov/apod/lib/apsubmit2015.html 18. https://apod.nasa.gov/apod/lib/aptree.html 19. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 20. https://apod.nasa.gov/apod/calendar/allyears.html 21. https://apod.nasa.gov/apod.rss 22. https://apod.nasa.gov/apod/lib/edlinks.html 23. https://apod.nasa.gov/apod/lib/about_apod.html 24. http://asterisk.apod.com/discuss_apod.php?date=190829 25. https://apod.nasa.gov/apod/ap190830.html 26. http://www.phy.mtu.edu/faculty/Nemiroff.html 27. http://www.phy.mtu.edu/ 28. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 29. http://www.astro.umd.edu/ 30. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 31. https://www.nasa.gov/about/highlights/HP_Privacy.html 32. https://astrophysics.gsfc.nasa.gov/ 33. https://www.nasa.gov/ 34. https://www.nasa.gov/centers/goddard/ 35. http://www.mtu.edu/