For many centuries, people have struggled with the solar system to sync the civic, religious, and agricultural calendars. Adding a 'leap year' solved the problem - though for the next 3,300 years.
Next Saturday, February 29th it's that time again, is a leap day, the calendar oddity that happens every four years (about).
For many centuries, trying to sync a calendar with the length of a natural year has sowed chaos - until the idea of a leap year provides a way to make up for the lost time.
John Lowe who led the National Institute of Standards and Technology (NIST)’s Time & Frequency Division until his retirement, says: “It all comes down to the fact that the number of Earth’s revolutions about its own axis, or days, is not connected in any way to how long it takes for the Earth to get around the sun.”
A solar year is approximately 365.2422 days long. No calendar consists of whole days can equal that number, and just ignoring the apparently small fraction makes a much bigger problem than one might suspect.
Attempts to make the schedule of nature our own have been incomplete from the beginning. Early Egyptians (prior to about 3100 B.C.) and other communities from China to Rome at one time used lunar calendars to track time.
But lunar months approximately 29.5 days and years only about 354. So communities that kept lunar time rapidly derived well out of sync with the seasons due to the 11-day lag.
By the time Julius Caesar delighted his famous affair with Cleopatra, Rome’s lunar calendar had separate from the seasons by some three months—despite efforts to tweak it by irregularly attach days or months to the year.
Between the time Caesar initiated the system and the 16th century, this small clash had caused important dates, including the Christian holidays, to drift by some 10 days.
Even today, some calendars discount the leap year signifies to keep us in time with our orbit, while others ignore the sun completely.
The present Gregorian calendar system creates the fractional days of the solar year and leap year calendar nearly the same by occasionally skipping a leap day.
Source: National Geographic