[00:03.27]Part 1 American Mosaic
[00:08.20]Text 1 Leap Year
[00:29.78]February has an extra day this year because the year 2,000 is a "leap year".
[00:36.57]That means that one day is added to the calendar.
[00:40.86]That day is February twenty-ninth, also known as "Leap Day".
[00:47.44]Leap days were added to some years to make the calendar year
[00:52.43]nearly the same as the time it takes the Earth to travel around the sun.
[00:57.99]That is exactly 365 days, 5 hours, 48 minutes and a little over 45 seconds.
[01:08.88]So our calendar year is either 365 days in non-leap years or 366 days in leap years.
[01:08.94]The leap year was first used in the Julian Calendar 2,046 years ago.
[01:16.64]It was developed by the Roman Emperor Julius Caesar.
[01:21.16]In the Julian calendar, each year contained twelve months
[01:26.28]and had an average of 365 and one-fourth days in a year.
[01:33.07]This was done by having three years of 365 days and one year of 366 days: a leap day every four years.
[01:47.13]However, after Julius Caesar died,
[01:50.63]it was discovered that the priests who wrote the yearly calendars had been adding leap days every three years instead of every four.
[02:00.71]As a result, no more leap days were added for many years.
[02:06.54]By 1582, Pope Gregory the Thirteenth recognized that the calendar had too many leap days.
[02:16.10]If this continued, the seasons would start on different days each year.
[02:22.71]Over time,for example, this would cause the holiday of Easter to move closer and closer to Christmas.
[02:32.16]So Pope Gregory changed the calendar.
[02:35.69]It became known as the Gregorian Calendar. It is the one that is used most today.
[02:43.60]Pope Gregory's calendar continued to have leap days every four years, with an exception.
[02:51.21]Years ending in zerozero were leap years only if they could be divided by 400.
[02:59.83]So this year is a leap year, but 1900 was not.
[03:05.76]February 29, 2000 will be the first leap day in a century year since the year 1600. |