Leap day is added because it takes the Earth 365 days, five hours, 48 minutes and 45 seconds to orbit the sun -- almost an extra quarter of a day per year. If you count the quarter of a day up for each year, you get an extra day added every fourth year.
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With the extra day comes extra intrigue. According to folk tradition, marriage-minded women could propose to their boyfriends on leap day. And legend has it that in Scotland, any man who refused would be issued a fine.
In Greece, however, leap year is considered unlucky. Marriages in a leap year will end in divorce, according to superstition.
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Moms have a one in 1,461 chance of giving birth on leap day, meaning only 0.07% of the population are so-called "leapers."
For some, being a leaper is special, especially for Mary Ann Brown, who started a party for her fellow Feb. 29 babies in 1988. Her hometown, Anthony, Texas, has thrown a party every leap year since and has declared itself "Leap Year Capital of the World."
Every year since, the town has invited leapers from all over the world to celebrate with a Feb. 29 parade!