Leap years

[Goodsoulette]

What is the point in them?
When did we start having them? What would happen if we didnt have them?

[LazyGun]

Leap years contain an extra day in February: 29 days instead of the usual 28. Every year divisible by four is a leap year -- unless it's divisible by 100, in which case it's not, unless it's also divisible by 400, in which case it is. Got it?

The purpose of a leap year is to align the calendar year with the astronomical year. While the calendar year holds 365 days, it actually takes the earth 365.2422 days to revolve around the sun. This extra six hours a year can add up -- if we didn't have leap years, we'd be out of sync by 28 days every 100 years.

So summer would eventually creep into fall, and eventually winter, and so on. For us in the Northern Hemisphere, it would be very strange to have short, frigid days in July. The Romans realized this, which is why they decreed the first leap year in 46 B.C.

However, adding an extra day every four years is actually too much of a correction (hence the need for the rules about being divisible by 400 versus 100). No calendar is perfect, but the Gregorian seems to work fairly well.

[Loosehead]

excellent answer by lazygun.

You can see an amplified effect of not having leap years by comparing the astronomical year with the Islamic year. The Islamic year still uses the moon as the base unit so it is roughly 11 days shorter each year. So the start of Ramadan is 11 days earlier each year. Now in the equatorial area where Islam started the variance of the seasons is very little but at UK latitude for example it wouldn't take long before winter was in June and Summer is at Christmas.

The Excellent book "The Calendar" by David Ewing Duncan explains the whole thing thoroughly.

[Goodsoulette]

Thank you both,.. I wa trying to figure it out earlier and couldnt get it... but that was a good leap year for dummies answer, and I got it totally (dont get me wrong I mean it)