OPEN YOUR CALENDARS AND OBSERVE OCTOBER OF 1582: THE JUMP FROM THE 4TH TO THE 15TH OF OCTOBER

Look at a calendar from 1582. You will see something really strange: October lost ten complete days! After Thursday the 4th, Friday the 15th comes directly. The intermediate days simply do not exist.

It was the doing of Pope Gregory XIII. He wanted to change the old Julian calendar for a new one that we call the Gregorian. The Julian calendar was not capable of accurately measuring the solar year. A discrepancy was accumulating over time. Quite annoying.

To fix this mess with the astronomical cycles, especially the spring equinox, someone made a radical decision. To eliminate ten days all at once. Just like that. In Spain, Italy, and other countries, people went to bed on a Thursday and woke up... but it was Friday of the following week. It seems like a cruel joke, doesn’t it?

The reform also brought new rules for leap years. It is the same system we use today. It turns out to be much more accurate for measuring time in the long term, although it is not perfect in every way. We continue with it.