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. 2024 December 19 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Messier 2 Image Credit: [3]ESA/Hubble & [4]NASA, [5]G. Piotto et al. Explanation: [6]After the Crab Nebula, this giant star cluster is the second entry in 18th century astronomer Charles Messier's famous list of things that are not comets. M2 is one of the largest globular star clusters now known to roam the halo of our Milky Way galaxy. Though Messier originally described it as a nebula without stars, this [7]stunning Hubble image resolves stars across the cluster's central 40 light-years. [8]Its population of stars numbers close to 150,000, concentrated within a total diameter of around 175 light-years. About 55,000 light-years distant toward the constellation Aquarius, this ancient denizen of the Milky Way, also [9]known as NGC 7089, is 13 billion years old. An extended [10]stellar debris stream, a signature of past gravitational tidal disruption, was recently found to be [11]associated with Messier 2. Tomorrow's picture: the last full moon __________________________________________________________________ [12]< | [13]Archive | [14]Submissions | [15]Index | [16]Search | [17]Calendar | [18]RSS | [19]Education | [20]About APOD | [21]Discuss | [22]> __________________________________________________________________ Authors & editors: [23]Robert Nemiroff ([24]MTU) & [25]Jerry Bonnell ([26]UMCP) NASA Official: Amber Straughn [27]Specific rights apply. [28]NASA Web Privacy Policy and Important Notices A service of: [29]ASD at [30]NASA / [31]GSFC, [32]NASA Science Activation & [33]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2412/potw1913aa.jpg 3. https://spacetelescope.org/ 4. https://www.nasa.gov/ 5. https://arxiv.org/abs/1410.4564 6. https://apod.nasa.gov/apod/ap180104.html 7. https://spacetelescope.org/images/potw1913a/ 8. http://www.messier.seds.org/m/m002.html 9. https://arxiv.org/abs/1606.05949 10. https://apod.nasa.gov/apod/ap240927.html 11. https://ui.adsabs.harvard.edu/abs/2022ApJ...929...89G/abstract 12. https://apod.nasa.gov/apod/ap241218.html 13. https://apod.nasa.gov/apod/archivepix.html 14. https://apod.nasa.gov/apod/lib/apsubmit2015.html 15. https://apod.nasa.gov/apod/lib/aptree.html 16. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 17. https://apod.nasa.gov/apod/calendar/allyears.html 18. https://apod.nasa.gov/apod.rss 19. https://apod.nasa.gov/apod/lib/edlinks.html 20. https://apod.nasa.gov/apod/lib/about_apod.html 21. http://asterisk.apod.com/discuss_apod.php?date=241219 22. https://apod.nasa.gov/apod/ap241220.html 23. http://www.phy.mtu.edu/faculty/Nemiroff.html 24. http://www.phy.mtu.edu/ 25. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 26. http://www.astro.umd.edu/ 27. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 28. https://www.nasa.gov/about/highlights/HP_Privacy.html 29. https://astrophysics.gsfc.nasa.gov/ 30. https://www.nasa.gov/ 31. https://www.nasa.gov/centers/goddard/ 32. https://science.nasa.gov/learners 33. http://www.mtu.edu/