Girlawhirl learned a leap year – or intercalary year – goes back to none other than Julius Caesar. Back in 45BC the Roman Emperor created a 12-month, 365-day year calendar, including an extra day every fourth February. But it wasn’t precise – in reality it was too long by 11 minutes and 14 seconds.

By the 16^th Century, the Spring Solstice on the calendar was actually 10 days too soon. So Pope Gregory XIII decided to create a new calendar, the one still used today. Pope Gregory adjusted the date of the Spring Solstice by 11 days and added a new rule for leap years. Under the new calendar, a century year is only a leap year if it is divisible by 400. For example, 2000 was a leap year, but 1900 wasn’t, and 2100 won’t be.

Under the Gregorian calendar, it will take 3,000 years before a day is gained in error.

Click here to visit infoplease.com for more information on leap years.