How is a leap second related to a leap year?
Leap seconds and leap years are both implemented to keep our time in accordance with the position of Earth. However, leap seconds are added when needed, based on measurements, and leap years are regularly occurring events based on set rules. During leap years, an extra day is added as February 29th to keep the calendar synchronized with the precession of the Earth around the Sun. Leap years are necessary because the actual length of the year is 365.2422 days and not 365. The extra day is added every four years to compensate for most of the partial day. However, this is a slight over-compensation, so some century years are not leap years. Only every fourth century year (those equally divisible by 400) is a leap year. For instance, 2000 was a leap year, but 1900, 1800 and 1700 were not. For additional information about leap years, please see the exhibit on calendars.
