Innovative developments in photography made it possible to obtain telescopic images of distant celestial bodies, which could then be observed and analyzed over extended periods of time.
Astronomical photography dates back to the origins of the new technology: one of the first objects Louis Daguerre (1787-1851) attempted to reproduce was the Moon, and the oldest existing daguerreotype of Earth’s satellite was taken in 1840 by the English photographer John William Draper (1811-1882).
At the Spatial Observatory of the Collegio Romano, Jesuit scientist Angelo Secchi (1818-1878) was among the first to turn to photography: he attempted to capture the total solar eclipse of 1851, and in 1858 published his Photographic Maps of the Principal Lunar Phases, the world’s first atlas of the Moon.
While studying the solar corona and solar flares, Secchi realized that photography would be a decisive aid in defining the nature of such phenomena. On the occasion of the solar eclipse of July 18, 1860, he organized a scientific expedition into the desert of Las Palmas, in Spain, where he obtained images of the phase of total eclipse. By comparing Secchi’s photographs with those taken at Rivabellosa by British astronomer Warren De la Rue (1815-1889), it became possible to demonstrate that solar flares are actual physical phenomena, thus confirming the importance of photography to the study of astronomical phenomena.
By the end of the nineteenth century astronomical photography had become so advanced that it was possible to undertake a heretofore unimaginable enterprise: to create a photographic map of the entire sky, the Carte du Ciel.