To Pope Gregory XIII owes the first chronological perplexity of the modern age, and Gregory's reform caused little of it. Here are the facts. Things are not going well over time in Europe in the 16th century AD, which started in 1501. The truth is that Holy Easter manifests itself in an increasingly warmer season each year. After consulting with the astronomers, the Pope realizes that the reason for the delay was due to the mild "dyscrasia" between the tropical and Julian years. The tropical year is nothing more than the time it takes for the Earth to make a complete rotation around the Sun. It takes exactly: 365.
The Julian year Caesar wanted in the calendar reform was initiated in the model known in Egypt in 45 BC, instead lasting 11 minutes 14 seconds longer for pure mathematical convenience and 365.25 days. The arithmetic ease lies in the fact that three years of 365 days can be replaced by 366 years to maintain synchronization between legal and astronomical time. It is true that between the tropical year and the year of Caesar, there is an 11-minute gap and change left. But the error is small: equal to 0.002%. The problem is that time sometimes magnifies even minor mistakes. So after 1500 years, discrasias is a dozen days.
On the advice of astronomers, to stop legal time from slipping between seasons, Pope Gregory orders us to stop thinking of leap years as leap years ending in double zeros; Like 1800 and 2000, we can be divided by four. And above all, Pope Gregory XIII orders us to move directly from Thursday, October 4, in the year of grace 1582, to Friday, October 15, in a single night.
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