What is a leap year?
Q: What is a leap year?
A: A leap year is a year in which an extra day is added to the Gregorian calendar, making it have 366 days instead of 365. This extra day is called a leap day and occurs on February 29.
Q: How often do leap years occur?
A: In the Gregorian calendar, 97 out of every 400 years are leap years. In the outdated Julian calendar, 100 years out of every 400 are leap years. All other years are common years.
Q: Why do we have leap years?
A: We have leap years because instead of 365 days, the Earth really takes a few minutes less than 365-1/4 days (365.24219) to go completely around the Sun. Without them, the seasons would start one day earlier on the calendar every four years.
Q: What countries use lunar calendars?
A: A number of countries use a lunar calendar (based on the Moon, instead of the Sun). They add an extra lunar month for their version of a leap year.
Q: How does adding an extra month work in different calendars?
A: Different calendars add the extra month in different ways so that they can account for having 366 days instead of 365 in their version of a leap year.
Q: Are all evenly divisible by 4 numbers considered as Leap Years?
A: No, any year that is evenly divided by 100 would not be considered as a Leap Year unless it is also evenly divided by 400; this explains why 1600, 2000 and 2400 are Leap Years while 1700, 1800, 1900 2100 2200 and 2300 are not even though they are all divisible by 4.
