Aloysius Lilius (c. 1510 – 1576), also variously referred to as Luigi Lilio or Luigi Giglio, was an Italian physician, astronomer, philosopher and chronologist, and also the "primary author" who provided the proposal that (after modifications) became the basis of the Gregorian Calendar reform of 1582. The crater Lilius on the Moon is named after him, as is the asteroid 2346 Lilio. In computer science, the Lilian date is the number of days since the adoption of the Gregorian calendar on 15 October 1582. Source: Wikipedia (en)