A photograph of the Sun, from 'Autographs of the Sun' by John Titterton, taken with the Heliautograph of Reverend William Selwyn of Ely. The photographer has noted that it was taken at 9.45 am, information vital for noting patterns of change in the Sun's appearance. This series of photographs highlights the sunspots that photographers attempted to record with great interest. These are regions of unusually high magnetic field in the photosphere. Cooler than the surrounding areas, they look darker, appearing and disappearing periodically. Research into the sunspots by astronomer Richard Christopher Carrington prompted calls for photographers to assist in recording details. Sir John Herschel asked photographers to make daily records of the Sun's appearance, in particular the variation of these spots.
© National Museum of Science & Media / Science & Society Picture Library