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 August 6 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Messier 20 and 21 Image Credit & [3]Copyright: [4]Emanuele Petrilli Explanation: [5]The beautiful Trifid Nebula, also known as Messier 20, is easy [6]to find with a small telescope in the nebula rich constellation Sagittarius. About 5,000 light-years away, the colorful study in [7]cosmic contrasts shares this well-composed, nearly 1 degree wide field with open star cluster [8]Messier 21 (right). Trisected by dust lanes the Trifid itself is about 40 light-years across and a mere 300,000 years old. That makes it one of the [9]youngest star forming regions in our sky, with newborn and embryonic stars embedded in its [10]natal dust and gas clouds. Estimates of the distance to open star cluster M21 are similar to M20's, but though they share this gorgeous telescopic skyscape there is no apparent connection between the two. In fact, M21's stars are much older, about 8 million years old. Tomorrow's picture: dark markings __________________________________________________________________ [11]< | [12]Archive | [13]Submissions | [14]Index | [15]Search | [16]Calendar | [17]RSS | [18]Education | [19]About APOD | [20]Discuss | [21]> __________________________________________________________________ Authors & editors: [22]Robert Nemiroff ([23]MTU) & [24]Jerry Bonnell ([25]UMCP) NASA Official: Phillip Newman [26]Specific rights apply. [27]NASA Web Privacy Policy and Important Notices A service of: [28]ASD at [29]NASA / [30]GSFC & [31]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2008/trifidnebulaM20M21_2048.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. https://www.instagram.com/_petrilli/ 5. https://apod.nasa.gov/apod/ap171020.html 6. http://freestarcharts.com/index.php/messier-catalogue/20-guides/messier/259-messier-20-m20-trifid-nebula-emission-and-reflection-nebula 7. http://www.cosmotography.com/images/cosmic_nurseries.html 8. http://www.universetoday.com/31935/messier-21/ 9. http://arxiv.org/abs/astro-ph/0107111 10. http://www.spitzer.caltech.edu/news/184-ssc2005-02-Spitzer-Finds-Stellar-Incubators-with-Massive-Star-Embryos 11. https://apod.nasa.gov/apod/ap200805.html 12. https://apod.nasa.gov/apod/archivepix.html 13. https://apod.nasa.gov/apod/lib/apsubmit2015.html 14. https://apod.nasa.gov/apod/lib/aptree.html 15. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 16. https://apod.nasa.gov/apod/calendar/allyears.html 17. https://apod.nasa.gov/apod.rss 18. https://apod.nasa.gov/apod/lib/edlinks.html 19. https://apod.nasa.gov/apod/lib/about_apod.html 20. http://asterisk.apod.com/discuss_apod.php?date=200806 21. https://apod.nasa.gov/apod/ap200807.html 22. http://www.phy.mtu.edu/faculty/Nemiroff.html 23. http://www.phy.mtu.edu/ 24. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 25. http://www.astro.umd.edu/ 26. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 27. https://www.nasa.gov/about/highlights/HP_Privacy.html 28. https://astrophysics.gsfc.nasa.gov/ 29. https://www.nasa.gov/ 30. https://www.nasa.gov/centers/goddard/ 31. http://www.mtu.edu/