1871: Death of John Herschel (born 1792), a central figure in British astronomy and mathematics. His legacy includes the first systematic mapping of the Southern Hemisphere sky, completing the work of his father, William, as well as the identification of thousands of double stars and nebulae. A pioneer of photochemistry, he invented the cyanotype process and introduced the fundamental concepts of "photography", "negative", and "positive", thus unifying celestial observation with the chemical fixing of the image.

Image credits : nasa.gov