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 October 19 [2]The picture shows the globular star cluster Palomar 6 as imaged by the Hubble Space Telescope. Please see the explanation for more detailed information. Palomar 6: Globular Star Cluster Image Credit: [3]ESA/[4]Hubble and [5]NASA, R. Cohen Explanation: Where did this big ball of stars come from? [6]Palomar 6 is one of about 200 [7]globular clusters of stars that survive in [8]our Milky Way Galaxy. These spherical star-balls are older than [9]our Sun as well as older than most stars that orbit in our [10]galaxy's disk. Palomar 6 itself is estimated to be about 12.5 billion years old, so old that it is close to -- [11]and so constrains -- the age of the [12]entire universe. Containing about 500,000 stars, [13]Palomar 6 lies about 25,000 [14]light years away, but not very far from our [15]galaxy's center. At that distance, [16]this sharp image from the [17]Hubble Space Telescope spans about 15 light-years. After [18]much study including images from Hubble, a [19]leading origin hypothesis is that Palomar 6 was created -- and survives today -- in the [20]central bulge of stars that surround the [21]Milky Way's center, not in the distant [22]galactic halo where most other [23]globular clusters are now found. Tomorrow's picture: lucy in the sky __________________________________________________________________ [24]< | [25]Archive | [26]Submissions | [27]Index | [28]Search | [29]Calendar | [30]RSS | [31]Education | [32]About APOD | [33]Discuss | [34]> __________________________________________________________________ Authors & editors: [35]Robert Nemiroff ([36]MTU) & [37]Jerry Bonnell ([38]UMCP) NASA Official: Phillip Newman [39]Specific rights apply. [40]NASA Web Privacy Policy and Important Notices A service of: [41]ASD at [42]NASA / [43]GSFC & [44]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2110/Palomar6_Hubble_2529.jpg 3. https://www.esa.int/ 4. https://esahubble.org/ 5. https://www.nasa.gov/ 6. https://en.wikipedia.org/wiki/Palomar_6 7. https://en.wikipedia.org/wiki/Globular_cluster 8. https://imagine.gsfc.nasa.gov/science/objects/milkyway1.html 9. https://solarsystem.nasa.gov/solar-system/sun/overview/ 10. https://astronomy.swin.edu.au/cosmos/d/Disk+Galaxies 11. https://wmap.gsfc.nasa.gov/universe/uni_age.html 12. https://science.nasa.gov/science-news/science-at-nasa/2013/21mar_cmb 13. https://ui.adsabs.harvard.edu/abs/2021arXiv210904483S/abstract 14. https://spaceplace.nasa.gov/light-year/en/ 15. https://apod.nasa.gov/apod/ap180729.html 16. https://esahubble.org/images/potw2138a/ 17. https://www.nasa.gov/mission_pages/hubble/about 18. https://i.ytimg.com/vi/5sjKUrBsaIE/hqdefault.jpg 19. https://arxiv.org/pdf/2109.04483.pdf 20. https://en.wikipedia.org/wiki/Galactic_bulge 21. https://apod.nasa.gov/apod/ap190708.html 22. https://en.wikipedia.org/wiki/Stellar_halo 23. https://apod.nasa.gov/apod/ap190324.html 24. https://apod.nasa.gov/apod/ap211018.html 25. https://apod.nasa.gov/apod/archivepix.html 26. https://apod.nasa.gov/apod/lib/apsubmit2015.html 27. https://apod.nasa.gov/apod/lib/aptree.html 28. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 29. https://apod.nasa.gov/apod/calendar/allyears.html 30. https://apod.nasa.gov/apod.rss 31. https://apod.nasa.gov/apod/lib/edlinks.html 32. https://apod.nasa.gov/apod/lib/about_apod.html 33. http://asterisk.apod.com/discuss_apod.php?date=211019 34. https://apod.nasa.gov/apod/ap211020.html 35. http://www.phy.mtu.edu/faculty/Nemiroff.html 36. http://www.phy.mtu.edu/ 37. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 38. http://www.astro.umd.edu/ 39. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 40. https://www.nasa.gov/about/highlights/HP_Privacy.html 41. https://astrophysics.gsfc.nasa.gov/ 42. https://www.nasa.gov/ 43. https://www.nasa.gov/centers/goddard/ 44. http://www.mtu.edu/