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 3 [2]See Explanation. Clicking on the picture will download the highest resolution version available. A Halo for Andromeda Digital Illustration Credit: [3]NASA, [4]ESA, J. DePasquale and E. Wheatley ([5]STScI) and Z. Levay Explanation: M31, the Andromeda Galaxy, is the closest large spiral galaxy to our Milky Way. Some 2.5 million light-years distant it shines in Earth's night sky as a small, faint, elongated cloud just visible to the unaided eye. Invisible to the eye though, its enormous halo of hot ionized gas is represented in purplish hues for [6]this digital illustration of our neighboring galaxy [7]above rocky terrain. Mapped by Hubble Space Telescope observations of the absorption of ultraviolet light against distant quasars, the extent and make-up of Andromeda's gaseous halo has been [8]recently determined by the AMIGA project. A reservoir of material for future star formation, Andromeda's halo of diffuse [9]plasma was measured to extend around 1.3 million light-years or more from the galaxy. That's about half way to the Milky Way, likely putting it in contact with the diffuse gaseous halo of our own galaxy. Tomorrow's picture: pixels in space __________________________________________________________________ [10]< | [11]Archive | [12]Submissions | [13]Index | [14]Search | [15]Calendar | [16]RSS | [17]Education | [18]About APOD | [19]Discuss | [20]> __________________________________________________________________ Authors & editors: [21]Robert Nemiroff ([22]MTU) & [23]Jerry Bonnell ([24]UMCP) NASA Official: Phillip Newman [25]Specific rights apply. [26]NASA Web Privacy Policy and Important Notices A service of: [27]ASD at [28]NASA / [29]GSFC & [30]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2009/STScI-H-p2046b-m-1999x2000.jpg 3. https://www.nasa.gov/ 4. https://www.spacetelescope.org/ 5. https://www.stsci.edu/ 6. https://hubblesite.org/contents/media/images/2020/46/4735-Image 7. https://apod.nasa.gov/apod/ap200326.html 8. https://hubblesite.org/contents/news-releases/2020/news-2020-46 9. https://arxiv.org/abs/2002.07818 10. https://apod.nasa.gov/apod/ap200902.html 11. https://apod.nasa.gov/apod/archivepix.html 12. https://apod.nasa.gov/apod/lib/apsubmit2015.html 13. https://apod.nasa.gov/apod/lib/aptree.html 14. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 15. https://apod.nasa.gov/apod/calendar/allyears.html 16. https://apod.nasa.gov/apod.rss 17. https://apod.nasa.gov/apod/lib/edlinks.html 18. https://apod.nasa.gov/apod/lib/about_apod.html 19. http://asterisk.apod.com/discuss_apod.php?date=200903 20. https://apod.nasa.gov/apod/ap200904.html 21. http://www.phy.mtu.edu/faculty/Nemiroff.html 22. http://www.phy.mtu.edu/ 23. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 24. http://www.astro.umd.edu/ 25. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 26. https://www.nasa.gov/about/highlights/HP_Privacy.html 27. https://astrophysics.gsfc.nasa.gov/ 28. https://www.nasa.gov/ 29. https://www.nasa.gov/centers/goddard/ 30. http://www.mtu.edu/