Aloysius Lilius - Life and Work

Life and Work

Not much is known about the early life of Lilius/Lilio/Giglio. It is known that he came from Calabria, Italy, from Cirò (or Zirò). He studied medicine and astronomy in Naples, after which he served Earl Carafa. He settled in Verona and died in 1576. Although he was still alive at the time when his proposal was presented at Rome, it does not seem that he made the presentation; it was handled by his brother Antonio, also a physician and astronomer.

He is primarily known as the "first author" of the Gregorian Calendar: he wrote the proposal on which (after modifications) the calendar reform was based. Lilio's brother Antonio presented the manuscript to Pope Gregory XIII; it was passed to the calendar reform commission in 1575. The commission issued a printed summary entitled Compendium novae rationis restituendi kalendarium (Compendium of a New Plan for the Restitution of the Calendar), printed in 1577 and circulated within the Roman Catholic world in early 1578 as a consultation document. Lilio's manuscript itself is not known to have survived; the printed 'Compendium' is the nearest known source for the details it contained.

The processes of consultation and deliberation meant that the reform to the calendar did not occur until 1582, six years after the death of Luigi Lilio in 1576. The reform had by then received some modifications in points of detail by the reform commission, in which one of the leading members was Clavius, who afterwards wrote defences and an explanation of the reformed calendar, including an emphatic acknowledgement of Lilio's work, especially for his provision of a useful reform for the lunar cycle: "We owe much gratitude and praise to Luigi Giglio who contrived such an ingenious Cycle of Epacts which, inserted in the calendar, always shows the new moon and so can be easily adapted to any length of the year, if only at the right moments the due adjustment is applied." The papal bull (Inter gravissimas) was issued on 24 February 1582, ordering Catholic clergy to adopt the new calendar, and exhorting Catholic sovereigns to do the same.

The year 2010 is the 500th year since the Lilius' birth; several activities have been organized (by Italian astronomers) in order to recognize the great work performed by him. In particular, in Torretta di Crucoli (Crotone, Italy), a new astronomical group has been created and dedicated to Luigi Lilio: Circolo Astrofili Luigi Lilio Torretta (C.A.L.L.T.)