Answer:
We add an extra day to the calendar every four years to make up for the extra quarter day we have every year.
Explanation:
- The modern Gregorian Calendar that we follow allows for the adjustment of the extra quarter day that we have every year simply by adding another day to the month of February every four years.
- The actual time taken by Earth to complete one revolution around the Sun is approximately 365 days and 5 hours.
- To compensate for the 5 hours that we cease to consider every year, a day is added to the fourth year which we refer to as leap year.