By Rosario A. Iaconis
Luigi Lilio (1510 -1576), the Italian physician, astronomer, and philosopher who was born in Cirò, Calabria, invented the Gregorian calendar that we use today.
Utilizing astronomical data contained in tables from the prior three centuries, Luigi Lilio—a k a Aloysius Lilius in Latin—created a calendar that has withstood the test of time. With his profound knowledge of mathematics, Lilio synchronized the solar and lunar cycles to develop the epact cycle, which ascertained the precise Easter date celebration .
This revised calendar reformed the Julian calendar, which Julius Caesar had amended once before in 46 BC in order account for days in excess of 365. Lilio’s innovation aligned the date for the celebration of Easter back to the time of the year agreed upon by the First Council of Nicaea in 325 AD. Furthermore, the Lilian method offered the possibility of correcting the calendar according to the variation of leap days.
Luigi Lilio’s manuscript, Compendiuem novae rationis restituendi kalendarium (Compendium of the New Plan for the Restitution of the Calendar) was presented to Pope Gregory XIII after Lilio’s death. The actual adoption of this Gregorian calendar took place six years later
There is a crater on the moon named for Luigi Lilio, as well as a Lilian date, the number of days that have passed since the adoption of the Gregorian Calendar (October 15, 1582). In Calabria—March 21 (the day of the spring equinox)—is known as “Regional Calendar Day” in honor of Lilio.
Luigi Lilio’s Gregorian calendar remains the most common calendar in use in the world today, even by cultures that employ other calendars for various civil and religious reasons.