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 February 18
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                          Three Clusters in Puppis
                 Image Credit & [3]Copyright: [4]Dave Doctor

   Explanation: Galactic or [5]open star clusters are young. The swarms of
   stars are born together near the plane of the Milky Way, but their
   numbers [6]steadily dwindle as cluster members are ejected by galactic
   tides and gravitational interactions. Caught in [7]this telescopic
   frame over three degrees across are three good examples of galactic
   star clusters, seen toward the southern sky's nautical constellation
   [8]Puppis. Below and left, [9]M46 is some 5,500 light-years in the
   distance. Right of center [10]M47 is only 1,600 light-years away and
   NGC 2423 (top) is about 2500 light-years distant. Around 300 million
   years young M46 contains a few hundred stars in a region about 30
   light-years across. Sharp eyes can spot a planetary nebula, [11]NGC
   2438, at about 11 o'clock against the M46 cluster stars. But that
   nebula's [12]central star is billions of years old, and NGC 2438 is
   likely a foreground object only by chance along the line of sight to
   youthful M46. Even younger, aged around 80 million years, M47 is a
   smaller and looser star cluster spanning about 10 light-years. Star
   cluster NGC 2423 is pushing about 750 million years [13]in age though.
   NGC 2423 is known to harbor an extrasolar planet, [14]detected orbiting
   one of its red giant stars.

                    Tomorrow's picture: mammals in space
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    Authors & editors: [26]Robert Nemiroff ([27]MTU) & [28]Jerry Bonnell
                                 ([29]UMCP)
          NASA Official: Phillip Newman [30]Specific rights apply.
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                A service of: [32]ASD at [33]NASA / [34]GSFC
                           & [35]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2202/ThreeClustersPuppis.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://daveandtelescope.wordpress.com/
   5. http://messier.seds.org/open.html
   6. https://en.wikipedia.org/wiki/Open_cluster#Eventual_fate
   7. https://www.astrobin.com/ok6qec/
   8. http://hawastsoc.org/deepsky/pup/index.html
   9. https://www.universetoday.com/35075/messier-46/
  10. https://www.universetoday.com/35129/messier-47-star-cluster/
  11. https://apod.nasa.gov/apod/ap120403.html
  12. https://chandra.harvard.edu/xray_sources/white_dwarfs.html
  13. https://apod.nasa.gov/apod/ap171115.html
  14. https://arxiv.org/abs/0706.2174
  15. https://apod.nasa.gov/apod/ap220217.html
  16. https://apod.nasa.gov/apod/archivepix.html
  17. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  18. https://apod.nasa.gov/apod/lib/aptree.html
  19. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  20. https://apod.nasa.gov/apod/calendar/allyears.html
  21. https://apod.nasa.gov/apod.rss
  22. https://apod.nasa.gov/apod/lib/edlinks.html
  23. https://apod.nasa.gov/apod/lib/about_apod.html
  24. http://asterisk.apod.com/discuss_apod.php?date=220218
  25. https://apod.nasa.gov/apod/ap220219.html
  26. http://www.phy.mtu.edu/faculty/Nemiroff.html
  27. http://www.phy.mtu.edu/
  28. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  29. http://www.astro.umd.edu/
  30. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  31. https://www.nasa.gov/about/highlights/HP_Privacy.html
  32. https://astrophysics.gsfc.nasa.gov/
  33. https://www.nasa.gov/
  34. https://www.nasa.gov/centers/goddard/
  35. http://www.mtu.edu/