Open Cluster NGC 6520 from CFHT . ... Credit Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight , CFHT Explanation: Did you ever have a day when it felt like a dark cloud was following you around? For the open cluster of stars NGC 6520, every day is like this. On the left of the above picture are many of NGC 6520's bright blue stars. They formed only millions of years ago - much more recently than our ancient Sun which formed billions of years ago. ...