Click on the image for a full resolution version M4 or Messier 4 is a rather small sized globular cluster. It has about 30,000 stars (this deep, high resolution image shows more than 17,000 stars…), what compared with monster clusters like Omega Centauri (with about 10,000,000 stars) or NGC 104 (47 Tuc, with about 1,000,000 stars) makes it just … Continue reading MESSIER 4. NGC 6121