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. 2022 November 22 [2]The featured image shows two clusters of blue stars placed next to each other. Please see the explanation for more detailed information. A Double Star Cluster in Perseus Image Credit & Copyright: [3]Tommy Lease Explanation: Few star clusters this close to each other. Visible to the unaided eye from [4]dark sky areas, it was cataloged in [5]130 BC by Greek astronomer [6]Hipparchus. Some 7,000 light-years away, [7]this pair of [8]open star clusters is also an easy binocular target, a [9]striking starfield in the [10]northern constellation of the mythical Greek hero [11]Perseus. Now known as [12]h and chi Persei, or NGC 869 (above right) and [13]NGC 884, the clusters themselves are separated by only a few hundred [14]light-years and contain stars much younger and hotter than the [15]Sun. In addition to being physically close together, [16]the clusters' ages [17]based on their individual stars are similar - evidence that both [18]clusters were likely a product of the same [19]star-forming region. Tomorrow's picture: open space __________________________________________________________________ [20]< | [21]Archive | [22]Submissions | [23]Index | [24]Search | [25]Calendar | [26]RSS | [27]Education | [28]About APOD | [29]Discuss | [30]> __________________________________________________________________ Authors & editors: [31]Robert Nemiroff ([32]MTU) & [33]Jerry Bonnell ([34]UMCP) NASA Official: Phillip Newman [35]Specific rights apply. [36]NASA Web Privacy Policy and Important Notices A service of: [37]ASD at [38]NASA / [39]GSFC, [40]NASA Science Activation & [41]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2211/DoubleCluster_Lease_3756.jpg 3. https://www.instagram.com/colorado_astro/ 4. https://apod.nasa.gov/apod/ap200408.html 5. https://en.wikipedia.org/wiki/130_BC 6. https://en.wikipedia.org/wiki/Hipparchus 7. https://www.instagram.com/p/CkYcGXJOmPg/ 8. https://en.wikipedia.org/wiki/Open_cluster 9. https://www.intermountainpet.com/hubfs/Blog_Images/Dogs-tilting-their-heads.jpg 10. https://en.wikipedia.org/wiki/Perseus_(constellation) 11. https://en.wikipedia.org/wiki/Perseus 12. http://www.messier.seds.org/xtra/ngc/n0869.html 13. https://en.wikipedia.org/wiki/NGC_884 14. https://spaceplace.nasa.gov/light-year/en/ 15. https://solarsystem.nasa.gov/solar-system/sun/in-depth/ 16. https://apod.nasa.gov/apod/ap201118.html 17. https://ui.adsabs.harvard.edu/abs/2001AJ....122..248K/abstract 18. http://asterisk.apod.com/viewtopic.php?f=24&t=18009 19. https://science.nasa.gov/astrophysics/focus-areas/how-do-stars-form-and-evolve 20. https://apod.nasa.gov/apod/ap221121.html 21. https://apod.nasa.gov/apod/archivepix.html 22. https://apod.nasa.gov/apod/lib/apsubmit2015.html 23. https://apod.nasa.gov/apod/lib/aptree.html 24. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 25. https://apod.nasa.gov/apod/calendar/allyears.html 26. https://apod.nasa.gov/apod.rss 27. https://apod.nasa.gov/apod/lib/edlinks.html 28. https://apod.nasa.gov/apod/lib/about_apod.html 29. http://asterisk.apod.com/discuss_apod.php?date=221122 30. https://apod.nasa.gov/apod/ap221123.html 31. http://www.phy.mtu.edu/faculty/Nemiroff.html 32. http://www.phy.mtu.edu/ 33. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 34. http://www.astro.umd.edu/ 35. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 36. https://www.nasa.gov/about/highlights/HP_Privacy.html 37. https://astrophysics.gsfc.nasa.gov/ 38. https://www.nasa.gov/ 39. https://www.nasa.gov/centers/goddard/ 40. https://science.nasa.gov/learners 41. http://www.mtu.edu/