Part 1 American Mosaic
Text 1 Leap Year
February has an extra day this year because the year 2,000 is a "leap year".
That means that one day is added to the calendar.
That day is February twenty-ninth, also known as "Leap Day".
Leap days were added to some years to make the calendar year
nearly the same as the time it takes the Earth to travel around the sun.
That is exactly 365 days, 5 hours, 48 minutes and a little over 45 seconds.
So our calendar year is either 365 days in non-leap years or 366 days in leap years.
The leap year was first used in the Julian Calendar 2,046 years ago.
It was developed by the Roman Emperor Julius Caesar.
In the Julian calendar, each year contained twelve months
and had an average of 365 and one-fourth days in a year.
This was done by having three years of 365 days and one year of 366 days: a leap day every four years.
However, after Julius Caesar died,
it was discovered that the priests who wrote the yearly calendars had been adding leap days every three years instead of every four.
As a result, no more leap days were added for many years.
By 1582, Pope Gregory the Thirteenth recognized that the calendar had too many leap days.
If this continued, the seasons would start on different days each year.
Over time,for example, this would cause the holiday of Easter to move closer and closer to Christmas.
So Pope Gregory changed the calendar.
It became known as the Gregorian Calendar. It is the one that is used most today.
Pope Gregory's calendar continued to have leap days every four years, with an exception.
Years ending in zerozero were leap years only if they could be divided by 400.
So this year is a leap year, but 1900 was not.
February 29, 2000 will be the first leap day in a century year since the year 1600.