OPEN STAR CLUSTERS

The open star clusters NGC 869 and NGC 884 form the famous “double cluster” in the constellation of Perseus. The clusters mark the sword with which Perseus decapitated the Medusa. This double cluster has been known since ancient times, but for unknown reasons, Charles Messier did not include the Double Cluster in his famous catalog. NGC 869 (on the right) is the more compressed of the two and has more than 200 white and blue-white stars. NGC 884 to the east (left) contains about 150 stars. Both clusters are blue-shifted and are approaching the earth at a speed of approximately 21-22 km/s. This image was taken with the Canon T5i camera through the AT65EDQ refractor mounted on the EQ8.