Young Observers

Leap Year Leap Year Leap Year Leap

For example, the calendar we use has 365 days in one year, but it really takes the Earth about 365 1/4 days to completely go around the Sun in one year.
 

So to keep the calendars in tune with the Earth's seasons (or else we will end up eventually with winter in July), an extra day has to be added every four years. We add it to any year that can be divided by four evenly (such as 1992 and 1996). We call these "leap years" and the extra day is on February 29.

This would work well if one year was exactly 365 1/4 days long but it isn't. One year is just a bit less. To be exact, it is 365 days, 5 hours, 49 minutes and 12 seconds long !!

So to keep the calendars more in tune, the last year of each century is not a leap year (1700, 1800, 1900, etc) unless it can be divided by 400 evenly. That makes this year 2000 very special because it is a leap year.

This page last modified: February 18, 2000 For comments or suggestions on this planet page, please write to Chris Teron