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 March 12 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Messier 81 Image Credit & [3]Copyright: [4]Wissam Ayoub Explanation: One of the brightest galaxies in planet Earth's sky is similar in size to our Milky Way Galaxy: big, [5]beautiful Messier 81. Also known as NGC 3031 or Bode's galaxy for its 18th century discoverer, [6]this grand spiral can be found toward the northern constellation of Ursa Major, the Great Bear. [7]The sharp, detailed telescopic view reveals M81's bright yellow nucleus, blue spiral arms, pinkish starforming regions, and sweeping [8]cosmic dust lanes. Some dust lanes actually run through the galactic disk (left of center), contrary to other prominent [9]spiral features though. The [10]errant dust lanes may be the lingering result of a [11]close encounter between M81 and the nearby galaxy M82 lurking outside of this frame. M81's faint, dwarf irregular satellite galaxy, Holmberg IX, can be seen just below the large spiral. Scrutiny of variable stars in M81 has yielded a [12]well-determined distance for an external galaxy -- 11.8 million light-years. Tomorrow's picture: one hand clapping __________________________________________________________________ [13]< | [14]Archive | [15]Submissions | [16]Index | [17]Search | [18]Calendar | [19]RSS | [20]Education | [21]About APOD | [22]Discuss | [23]> __________________________________________________________________ Authors & editors: [24]Robert Nemiroff ([25]MTU) & [26]Jerry Bonnell ([27]UMCP) NASA Official: Phillip Newman [28]Specific rights apply. [29]NASA Web Privacy Policy and Important Notices A service of: [30]ASD at [31]NASA / [32]GSFC & [33]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2103/BodesGalaxyM81.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. https://www.astrobin.com/users/Wissam_Astrophotography/ 5. https://www.universetoday.com/47054/messier-81-1/ 6. https://www.nasa.gov/feature/goddard/2017/messier-81 7. https://www.astrobin.com/c1jvyw/0/ 8. http://www.spitzer.caltech.edu/images/1070-ssc2003-06c-Spiral-Galaxy-Messier-81 9. http://burro.astr.cwru.edu/Academics/Astr222/Galaxies/Spiral/spiral.html 10. https://apod.nasa.gov/apod/ap010112.html 11. https://apod.nasa.gov/apod/ap200515.html 12. http://adsabs.harvard.edu/abs/1994ApJ...427..628F 13. https://apod.nasa.gov/apod/ap210311.html 14. https://apod.nasa.gov/apod/archivepix.html 15. https://apod.nasa.gov/apod/lib/apsubmit2015.html 16. https://apod.nasa.gov/apod/lib/aptree.html 17. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 18. https://apod.nasa.gov/apod/calendar/allyears.html 19. https://apod.nasa.gov/apod.rss 20. https://apod.nasa.gov/apod/lib/edlinks.html 21. https://apod.nasa.gov/apod/lib/about_apod.html 22. http://asterisk.apod.com/discuss_apod.php?date=210312 23. https://apod.nasa.gov/apod/ap210313.html 24. http://www.phy.mtu.edu/faculty/Nemiroff.html 25. http://www.phy.mtu.edu/ 26. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 27. http://www.astro.umd.edu/ 28. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 29. https://www.nasa.gov/about/highlights/HP_Privacy.html 30. https://astrophysics.gsfc.nasa.gov/ 31. https://www.nasa.gov/ 32. https://www.nasa.gov/centers/goddard/ 33. http://www.mtu.edu/