If you’ve never seen the three dark lanes in M13, known as “the propeller” please put it on your list of objects to observe.    

To read the full article on the Orion Telescope and Binocular site:  Go to the “Community Page” then “Deep-Sky Challenge” or just click on the following Orion link. 

http://www.telescope.com/Articles/Deep-Sky-Cluster/Globular-Cluster-M13-and-the-Elusive-Propeller/pc/-c/c/9/sc/770/p/102978.uts