Photo of the Week for January 12, 2018

Of the many open clusters scattered across the celestial sphere, few are as eye-catching as the Pleiades, also known as the Seven Sisters. Although the Pleiades are an obvious naked-eye sight, Charles Messier listed the cluster as M45 in his famous catalogue of non-comets. How could such a splendid collection of stars be mistaken for a comet? Consider a time when most comet discoveries were made without optical aid. Picture the Pleiades rising at dawn through a thick layer of atmospheric haze, and you can probably imagine how the cluster might be mistaken for a visitor from the cold, outer reaches of our solar system.

This lovely portrait of the Seven Sisters was captured last September by Ottawa astrophotographer, Joe Bonner. He digitally stacked 17, 7-minute frames acquired with a Canon EOS 6D DSLR camera (set to ISO 800) and an Orion ED80 80mm, f/7.5 refractor telescope to produce the finished image.