S NEAR AND FAR Open cluster NGC 6939 (top right) displays a mix of both blue and yellow stars. Its claim to fame is its proximity to face-on spiral NGC 6946, the Fireworks Galaxy, which has hosted 10 supernovae in the past 100 years. W ANCIENT STARS Top: NGC 6791 in Lyra is an old cluster thought to have formed nearly 8 billion years ago. All its hundreds of stars have left the main sequence and appear yellowish in photographs. W BUSY FIELD Bottom: M52 in Cassiopeia (upper left) is a rich open cluster with several hundred stars. Long exposures through a wide-field instrument will reward imagers with several reddish emission nebulae in its immediate vicinity, including NGC 7635, the Bubble Nebula, seen at lower right. s k y a n d t e l e s c o p e . o r g * J U LY 2 0 2 1 31http://www.skyandtelescope.org