Why is there a leap year?

Answer 1

Because the Earth doesn't complete a rotation is exactly 24 hours. It's just a bit more. To account for this ( and to keep the seasons in the same months throughout the millenniums ), we have an extra day every 4 years and on millennium years as well.

Answer 2

To compensate for the fact that every calendar year (365 days) is .25 days short of the exact number of days it actually takes the earth to go around the sun (365.25 days). Every four years those .25 days are added together to give an extra day, which is February 29th in leap years.

In fact, the real fraction is slightly less than .25 days. To compensate for this so every 100 years the leap year is skipped -- except for every 400 years, when it is not skipped.

(For the math inclined, every year divisible by 4 is a leap year EXCEPT those that are also divisible by 100 EXCEPT those that are also divisible by 400.)

Answer 3

The Earth travels around the Sun, makes one complete revolution around the Sun in almost exactly 365.25 days. Notice the .25. That quarter day is made up by multiplying times 4. Therefore every 4 years, we have a "Leap" year, with 366 days in that year to make up for the one-fourth day we missed the previous four.

Answer 4

The earth's years are actually 365.25 days long. Every four years, there's an extra day that goes unaccounted for.

It gets much more complicated than this, like how the last year of every century (1800, 1900, etc) does NOT have a leap year, but every fourth one of those (1600, 2000, 2400, etc) DOES have it. I think it all stems from the days being 23 hours and 56 minutes long.

Answer 5

there is a leap year because there are 365 and 1/4 days in a year, so the extra day is added on after 4 years to make an extra day

Answer 6

Because the average length of a year is 365.2425 days.

The calendar currently in worldwide use for secular purposes based on a cycle of 400 years comprising 146,097 days, giving a year of average length 365.2425 days.

The Gregorian calendar is a modification of the Julian calendar in which leap years are omitted in years divisible by 100 but not divisible by 400.

By this rule, the year 1900 was not a leap year (1900 is divisible by 100 and not divisible by 400), but the year 2000 will be a leap year (2000 is divisible by 400). The total number of days in 400 years is 146,097.

This also gives an exact number of 146,097/7 = 20,871 weeks per 400-year cycle.

The Gregorian calendar was constructed to give a close approximation to the tropical year, which is the actual length of time it takes for the Earth to complete one orbit around the Sun.

Answer 7

Contrary to what a couple of the answerers say, it's not based on the Earth's rotation on its axis, but to the earth's orbit around the sun. It actually takes closer to 365.24 or 365.23 days to go around the sun. Now orriginally we thought it was exactly .25, but later we found out it was a little shorter than that. So, every 4 years, to correct for that quarter of a day we lose in our journey around the sun, we tack on an extra day. But when they discovered that it's a little shorter, they decided that they needed to remove that extra bit of time. So every 100 years is not a leap year. But every 400 is to keep us from losing too much time.

Answer 8

The earth completes an orbit of the earth every 365 and 1/4 days, approximately. Every 4 years, a day is added to the calendar. Otherwise, summer and winter would eventually switch months.

Answer 9

Because a real year lasts 365 days AND 6 hours, so every 4 years you have 6x4=24 hrs, so you have 366 days.

Answer 10

To put it simply our calendar year is made up of 365.25 days. This is approximate and ever changing in the area of milliseconds, but every four years you get an extra day from the quarter days of the preceding three years added to the fourth year.