                        Astronomy Picture of the Day

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                    written by a professional astronomer.

                              2020 November 18

                      A Double Star Cluster in Perseus
                   Image Credit & Copyright: Greg Polanski

   Explanation: Most star clusters are singularly impressive. Open
   clusters NGC 869 and NGC 884, however, could be considered doubly
   impressive. Also known as "h and chi Persei", this unusual double
   cluster, shown above, is bright enough to be seen from a dark location
   without even binoculars. Although their discovery surely predates
   recorded history, the Greek astronomer Hipparchus notably cataloged the
   double cluster. The clusters are over 7,000 light years distant toward
   the constellation of Perseus, but are separated by only hundreds of
   light years. In addition to being physically close together, the
   clusters' ages based on their individual stars are similar - evidence
   that both clusters were likely a product of the same star-forming
   region.

                       Tomorrow's picture: open space
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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