Unwrapping the Visual Discovery of Spiral Nebula

For the May 14 meeting of the Santa Cruz Astronomy Club, Steve Gottlieb, a contributing editor for Sky & Telescope magazine, will be our featured speaker on "Unwrapping the Visual Discovery of Spiral Nebula". This is the story of William Parsons' (Third Earl of Rosse) first visual observations of M51 with his massive 72-inch speculum reflector in the spring of 1845 and the subsequent discovery of spiral structure in dozens of "nebulae". The context is how our biases and expectations affect our visual perception at the eyepiece. Eyepiece sketches of several spirals by Rosse and other mid-19th century observers will be presented along with my own observing experiences.