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. 2021 October 14 [2]See Explanation. Clicking on the picture will download the highest resolution version available. NGC 7293: The Helix Nebula Image Credit & [3]Copyright: [4]Ignacio Diaz Bobillo Explanation: A mere seven hundred light years from Earth, toward the constellation [5]Aquarius, a sun-like star is dying. Its last few thousand years have produced the [6]Helix Nebula (NGC 7293), a well studied and nearby example of a [7]Planetary Nebula, typical of this final phase of stellar evolution. A total of 90 hours of exposure time have gone in to creating [8]this expansive view of the nebula. Combining narrow band image data from emission lines of hydrogen atoms in red and oxygen atoms in blue-green hues, it shows remarkable [9]details of the Helix's brighter [10]inner region about 3 light-years across. The white dot at the Helix's center is this Planetary Nebula's hot, [11]central star. A simple looking nebula at [12]first glance, the Helix is now understood to have a surprisingly [13]complex geometry. Tomorrow's picture: pixels in space __________________________________________________________________ [14]< | [15]Archive | [16]Submissions | [17]Index | [18]Search | [19]Calendar | [20]RSS | [21]Education | [22]About APOD | [23]Discuss | [24]> __________________________________________________________________ Authors & editors: [25]Robert Nemiroff ([26]MTU) & [27]Jerry Bonnell ([28]UMCP) NASA Official: Phillip Newman [29]Specific rights apply. [30]NASA Web Privacy Policy and Important Notices A service of: [31]ASD at [32]NASA / [33]GSFC & [34]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2110/Helix_Oxygen_crop2.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. http://www.pampaskies.com/gallery3/index.php 5. http://hawastsoc.org/deepsky/aqr/index.html 6. https://en.wikipedia.org/wiki/Helix_Nebula 7. http://en.wikipedia.org/wiki/Planetary_nebula 8. http://www.pampaskies.com/gallery3/Deep-Space-Objects/Helix_Oxygen_crop2_small 9. https://apod.nasa.gov/apod/ap080413.html 10. https://apod.nasa.gov/apod/ap030510.html 11. https://hubblesite.org/contents/media/images/2003/11/1317-Image.html 12. https://apod.nasa.gov/apod/ap091231.html 13. https://hubblesite.org/contents/news-releases/2004/news-2004-32.html 14. https://apod.nasa.gov/apod/ap211013.html 15. https://apod.nasa.gov/apod/archivepix.html 16. https://apod.nasa.gov/apod/lib/apsubmit2015.html 17. https://apod.nasa.gov/apod/lib/aptree.html 18. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 19. https://apod.nasa.gov/apod/calendar/allyears.html 20. https://apod.nasa.gov/apod.rss 21. https://apod.nasa.gov/apod/lib/edlinks.html 22. https://apod.nasa.gov/apod/lib/about_apod.html 23. http://asterisk.apod.com/discuss_apod.php?date=211014 24. https://apod.nasa.gov/apod/ap211015.html 25. http://www.phy.mtu.edu/faculty/Nemiroff.html 26. http://www.phy.mtu.edu/ 27. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 28. http://www.astro.umd.edu/ 29. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 30. https://www.nasa.gov/about/highlights/HP_Privacy.html 31. https://astrophysics.gsfc.nasa.gov/ 32. https://www.nasa.gov/ 33. https://www.nasa.gov/centers/goddard/ 34. http://www.mtu.edu/