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Question of the Day
Question
How many days will February have in the year 2000?
Answer
The year 2000 is a normal leap year. The question arises because the year 1900 was not. Neither was 1800
or 1700. 1700, 1800, 1900 and 2000 are all divisible by 4, so why aren't they all leap years? And why do we
have leap years in the first place?
Let's start with the concept of a year. We define a year to be the amount of time it takes for the
earth to make one complete orbit around the sun. The reason we care about our orbital position
around the sun is because of the seasons. In the northern hemisphere we expect summer weather to
occur around June, July and August, and winter weather to occur in December, January and February.
A normal year is defined to be 365 days. However, if you measure the exact amount of time it takes for the
earth to orbit the sun, the number is actually 365.242199 days (according to Encyclopedia
Britannica). By adding one extra day to every 4th year, we get an average of 365.25 days per year, which is
fairly close to the actual number. To get even closer to the actual number, every 100 years is NOT a leap year,
but every 400 years IS a leap year. That brings the average length of the year to 365.2425 days, which is very close
to the actual number.
Putting all of these rules together you can see that it is a leap year if
the year is divisible by 4 or 400, but not if it is divisible by 100. So
1700, 1800 and 1900 were not leap years but 2000 is a leap year.
This all interrelates with the Year 2000 Problem because many computer programs
will calculate the leap year incorrectly in the year 2000. See the HSW article entitled How
The Year 2000 Problem Works for more information.
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Q&A Archive
Asking Questions
We all know that February is a funny month. Every four years it has one extra day (February 29th)
instead of the normal 28 days. When February has 29 days, we call it a "Leap Year". 1996 was a
leap year.
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