Wednesday Open Thread I’ll be tied up most of the morning. Will check back in when I can. A composite x-ray image shows the galaxy cluster 1E 0657-56, also known as the 'Bullet Cluster.' Most of the matter in the clusters (blue) is clearly separate from the normal matter (pink), giving direct evidence that nearly all of the matter in the clusters is dark. REUTERS/NASA Share this:PrintEmailFacebookTwitterGoogleTumblrPinterest Related Comments are closed.