1582 in science

The year 1582 in science and technology included a number of events, some of which are listed here. This year sees the introduction of the Gregorian calendar, promulgated by Pope Gregory XIII in the Papal bull Inter gravissimas on February 24 and based largely on the work of Christopher Clavius. Under the Habsburg monarchy in Spain, Portugal and Italy, together with the Polish–Lithuanian Commonwealth, the year continues under the Julian calendar as normal until Thursday October 4, the next day becoming Friday October 15; France follows two months later, letting Sunday December 9 be followed by Monday December 20. Other countries switch in later years.