Aimee Larson, age 14, of Columbus, Ohio, for her question:

WHY DO WE HAVE LEAP YEAR?

Leap years were added to the calendar to make the calendar year nearly the same as the solar year, which is the time required for the sun to pass the vernal equinox twice. An entire day is added to the end of February and so we have February 29 once every four years.

Leap year has 366 days instead of 365. A leap year happens in every year which can be divided evenly by four, except the years that mark the even hundreds, as 1900.

The only century years that are leap years are those that can be divided evenly by 400, such as 1600 and 2000.

Our last leap year came in 1988 and we will not be having our next until 1992.