Rosalind Franklin Captures X-ray Image of DNA

At King's College London, Rosalind Franklin and graduate student Raymond Gosling captured Photo 51, an X-ray diffraction image of hydrated B-form DNA after 100 hours of exposure at 92 percent relative humidity. The distinctive X-shaped pattern revealed DNA's helical structure, antiparallel strand arrangement, and phosphate backbone positioning. Without Franklin's knowledge, colleague Maurice Wilkins showed the photograph to James Watson and Francis Crick at Cambridge, who used its structural data to build their double helix model published in April 1953.