... Credit: N. A. Sharp ( NOAO ), AURA , NSF Explanation: Open clusters of stars can be near or far, young or old, and diffuse or compact. ... An older and more compact open cluster, NGC 2158 , is visible above on the lower right. ... NGC 2158's bright blue stars have self-destructed , leaving cluster light to be dominated by older and yellower star s. Both clusters are visible toward the constellation of Gemini -- M35 with binoculars and NGC 2158 with a small telescope. ... Star Cluster Messier 67 . ...