As a result, it wasn’t until 1582, by which time Caesar’s calendar had drifted a full 10 days off course, that Pope Gregory XIII (1502 - 1585) finally reformed the Julian calendar.

Ironically, by the time the Catholic church buckled under the weight of the scientific reasoning that pointed out the error, it had lost much of its power to implement the fix.

Egyptians also used a variation on this system, counting years based on years of a king's rule (so, an event might be dated to the 5th year of someone's rule) and then keeping a list of those kings.

But how did we get from that event-based organization to sticking with just one primary moment? is very easy for people to cope with because the life of Jesus is obviously incredibly important in Christian Europe.

This concerned Gregory because it meant that Easter, traditionally observed on March 21, fell further away from the spring equinox with each passing year. Leap years don’t really occur every four years in the Gregorian calendar.

The Julian calendar included an extra day in February every four years.

But even in a warm climate there are annual events that pay no attention to the phases of the Moon.

In some areas it was a rainy season; in Egypt it was the annual flooding of the Nile River.In colder countries, the concept of the year was determined by the seasons, specifically by the end of winter.But in warmer countries, where the seasons are less pronounced, the Moon became the basic unit for time reckoning; an old Jewish book says that “the Moon was created for the counting of the days.” Most of the oldest calendars were lunar calendars, based on the time interval from one new moon to the next—a so-called lunation.D." calendar designation first came into being, says Lynn Hunt, author of Measuring Time, Making History and professor of history at UCLA. For example, the Romans generally described years based on who was consul, or by counting from the founding of the city of Rome.Though there are a few frequently cited inflection points in that history—recorded instances of particular books using one system or another—the things that happened in the middle, and how and when new systems of dating were adopted, remain uncertain. Some might also count based on what year of an emperor's reign it was.One of the early writers to date this way was Dionysius Exiguus, a monk who, in 525 A. Terms referring to this "before" varied all the way through the 18th century.