SUNSET: 
0
Photographer:
Rod Pommier
Location of Photo:
Pommier Observatory, Portland, OR, USA
Date/Time of photo:
2024-05-30 through 2024-05-31
Equipment:
PlaneWave CDK17 on L500 mount, SBIG STL 11000 CCD camera with Baader Planetarium L, R, G, and B filters. Exposures: L:R:G:B = 245:40:40:40 minutes = 6 hours, 5 minutes total exposure, completely unguided.
Description:
M13 is a Shapley-Sawyer Class V globular cluster lying 25,000 light-years from Earth in the constellation Hercules. This image shows its unusual Y-shaped dark lanes in the clusters left upper quadrant quite well. This structure is now known as "The Propeller" due to its resemblance to a 3-bladed airplane propeller. This dark structure was first sketched by Irish astronomer Binden Stoney around 1850 using the Earl of Rosse's 72-inch Leviathan telescope at Birr Castle, Ireland. Whether the lanes are due to fewer stars in those regions or dark material in the cluster is hotly debated. However, that some globular clusters do contain dark obscuring material has been known since the early 1960s.
