This year has an extra day! Today is February 29th, although February usually has 28 days.
Leap year is every four years.
People born on February 29th are probably looking forward to today the most – this year they can finally celebrate their birthday again!
How do you know it’s a leap year? Here are three tips:
- if you can divide the year by four, it is a leap year,
- however, if you can divide it by 100, then it is not a leap year,
- but if you can divide it by 400, it is a leap year.
The rules may sound a bit complicated, but there is a good reason for leap years.
A calendar year is 365 days long, and an astronomical year is 365.2422 days. So they differ by five hours, 48 minutes, and 46 seconds.
Without the extra day every so often, we wouldn’t be aligned with the astronomical year. After a few centuries, Americans would celebrate Christmas on the beach and go skiing in June – and vice versa in Australia.
The leap year was first introduced 2,000 years ago by Julius Caesar. Before Caesar, Roman calendars were extremely out of sync with the astronomical year, so they had to add months to the calendar year to sync them.
Caesar thus introduced the Julian calendar, which had only one rule: every fourth year had an extra day – a leap year.
However, the difference between the years is not exactly six hours, so after sixteen centuries Pope Gregory XIII proposed a new calendar.
The Gregorian calendar is what we use today. It also takes into account minutes and seconds that do not coincide between the calendar year and the astronomical year.
Points to Consider
- Do you know a famous person born on February 29th?
- Will we celebrate a leap year in 2200?
- What about 2400?
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The original version of this article was published on 29th February.