Francesco Maria Grimaldi

Francesco Maria Grimaldi, who lived from 1618 to 1663, was an Italian Jesuit priest, mathematician and physicist who taught at the Jesuit college in Bologna, the city where he was born to Paride Grimaldi and Anna Cattani. Working with Giovanni Battista Riccioli between 1640 and 1650, he studied the free fall of bodies, confirming that distance fallen grows with the square of the time, and measured gravity at the Earth's surface with an accurate pendulum. In astronomy he built instruments to measure lunar mountains and the height of clouds and helped produce the lunar map published by Riccioli. He discovered and first carefully observed the diffraction of light and coined that word, setting out his findings in Physico-Mathesis de Lumine, Coloribus et Iride, published in 1665. Later physicists, including Huygens, used his work as evidence that light behaves as a wave.