Angelo Secchi was a key figure in 19th century science. An Italian Jesuit and scientist, he helped lead the transition from astronomy to astrophysics and left a lasting legacy in the field. Secchi's spectral classification of stars was a milestone that paved the way for modern astronomical research. He was also a founder of modern meteorology and an innovator in the design and development of new instruments and methods across disciplines.This contributed volume collects together reviews from an international group of historians, scientists and scholars representing the multiple disciplines where Secchi made significant contributions during his remarkable career. It analyzes both his famous and lesser known pioneering efforts with equal vigor, providing a well-rounded narrative of his life's work. Beyond his scientific and technological work, his role as a Jesuit priest in Rome during the turbulent years of the mid 19th century is also described and placed in the context of his scientific and civic activities.