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. 2023 January 20 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Galaxy Wars: M81 and M82 Image Credit & [3]Copyright: [4]Andreas Aufschnaiter Explanation: The two dominant galaxies near center are far far away, 12 million light-years distant toward the northern constellation of the Great Bear. On the right, with grand spiral arms and bright yellow core is [5]spiral galaxy M81. Also known as Bode's galaxy, M81 spans some 100,000 light-years. On the left is cigar-shaped [6]irregular galaxy M82. The pair have been locked in gravitational combat for a billion years. [7]Gravity from each galaxy has profoundly affected the other during a series of cosmic close encounters. Their last go-round lasted about 100 million years and likely raised density waves rippling around M81, resulting in the richness of [8]M81's spiral arms. [9]M82 was left with violent star forming regions and colliding gas clouds so energetic that the galaxy [10]glows in X-rays. In the next few billion years, their continuing gravitational encounters will result in a merger, and a [11]single galaxy will remain. This extragalactic scenario also includes other members of the interacting [12]M81 galaxy group with NGC 3077 below and right of the large spiral, and NGC 2976 at upper right in the frame. [13]Captured under dark night skies in the Austrian Alps, the foreground of the wide-field image is filled with integrated flux nebulae. Those faint, [14]dusty interstellar clouds reflect starlight above the plane of our own Milky Way galaxy. Tomorrow's picture: light-weekend __________________________________________________________________ [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]NASA Science Activation & [36]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2301/AUFSCHNAITER_Andreas_APOD_Bode_Cigare2048.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. https://www.instagram.com/aufschnaiter_photography/ 5. https://apod.nasa.gov/apod/ap190417.html 6. https://apod.nasa.gov/apod/ap190723.html 7. https://phys.org/news/2019-11-astronomers-stellar-halo.html 8. http://www.youtube.com/watch?v=0seVq5ydqzk 9. https://hubblesite.org/contents/news-releases/2001/news-2001-08.html 10. https://chandra.harvard.edu/photo/2006/m82/ 11. https://science.nasa.gov/science-news/science-at-nasa/2012/31may_andromeda/ 12. http://www.atlasoftheuniverse.com/galgrps/m81.html 13. https://www.instagram.com/p/CnSTIpuLZFV/ 14. https://apod.nasa.gov/apod/ap160428.html 15. https://apod.nasa.gov/apod/ap230119.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=230120 25. https://apod.nasa.gov/apod/ap230121.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. https://science.nasa.gov/learners 36. http://www.mtu.edu/