Jennifer Vernon 鄭鴻文

What is Leap Day？ What does it mean？ How was it calculated？ Read the passage below， then you'll know all—

Everyone knows that the month of February has only 28 days if not in a leap year（閏年）！ But every fourth year an extra day is added to the end of the month， creating a special day known as leap day， or February 29.

The leap day was created by Roman Emperor Julius Caesar in 46 B.C. Astronomers had calculated （計(jì)算） the time it takes for the Earth to circle the sun， the number was 365 days， plus about 6 hours. This extra bit of time would add up to approximately 24 hours， or one day， after four years.

Caesar's solution was to add an extra day at the end of February every fourth year. Later， scholars figured out that the extra amount of time was actually slightly less than six hours， and in 1582 A.D.， the Catholic Church altered the rule for calculating when a leap day would be added.

The new rule said that a leap day would be added every four years except in century years （years ending with two zeros）—unless that year could be evenly divided by 400.

Take the year 1900： It is a century year and is not evenly divisible by 400， so 1900 was not a leap year. However， the year 2000 is evenly divisible by 400， so it was a leap year.

Raenell Dawn， co-founder of the Honor Society for Leap Year Day Babies， likes to explain it this way： “You know when you're on a swing and you're swinging （擺動(dòng)） next to your friend， and you're not swinging in time—you're swinging opposite？ And then you're getting closer to swinging in time with each other， and then， all of a sudden， you're swinging right in time with each other！ That's the way the calendar was before leap days made the calendar year swing together with the solar year.”

During non-leap years， most “l(fā)eapers”， as people born on February 29 are known， celebrate their birthday either on February 28 or March 1. But when a real leap-day birthday occurs， many decide it's really time to party！

John Strohsacker went to school with two other kids who， like him， were born on February 29. He remembers his mother throwing big birthday parties for him and the two other leapers every time leap day rolled around. The whole class would be invited to attend.

“She took something that normally kids would probably tease you about， and she turned it around. You have this big party every four years， and so other kids are actually jealous—they wish they were born on leap day！” Strohsacker said.

Read the passage carefully and then answer the questions below.

1. How often does a leap year come？

2. What's the new rule for calculating when a leap day would be added？

3. Is adding leap days important？

4. Why would the whole class be invited to John Strohsacker's birthday party？