maddogkf

Our solar year is 365.24219 days.
History of Leap Year:

The Romans originally had a 355-day calendar. To keep up with the seasons, an extra 22 or 23-day month was inserted every second year, or so. They were not consistent in adding this month and by Julius Caesar’s time, the seasons no longer occurred at the same calendar periods as in the past. To correct this, Caesar eliminated the extra month and added one or two extra days to the end of various months. Thus extending the calendar to 365 days. He also intended an extra calendar day every fourth year (following the 28th day of Februarius). However, after Caesar’s death in 44 B.C., the calendars were written with an extra day every 3 years instead of every 4 until corrected in 8 A.D. So again, the calendar drifted away from the seasons.

By 1582, Pope Gregory XIII recognized that Easter would eventually become closer and closer to Christmas. The calendar was reformed so that a leap day would occur in any year that is divisible by 4 but not divisible by 100 except when the year is divisible by 400. Thus 1600 and 2000, although century marks, have a Leap Day.

We use the Gregorian calendar to this day. Our year of 365.2425 days, is only off from our solar year by .00031, which amounts to only one day’s error after 4,000 years.

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maddogkf

When Pope Gregory instituted the Gregorian Calendar, the Julian Calendar had been followed for over 1500 years, and so the calendar date had already drifted by over a week. Pope Gregory re-synchronized the calendar by simply eliminating 10 days! In 1582, the day after October 4th was October 15th!

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maddogkf

The Earth has two major components of motion. First, it spins on its rotational axis; a full spin rotation takes one Day to complete. Second, it orbits around the Sun; a full orbital rotation takes one Year to complete.

There are normally 365 days in one calendar year, but it turns out that a true year (i.e., a full orbit of the Earth around the Sun; also called a tropical year) is a little bit longer than 365 days. In other words, in the time it takes the Earth to complete one orbital circuit, it completes 365.24219 spin rotations. Don't be too suprised by this; there's no reason to expect the spin and orbital motions of the Earth to be synchronized in any way. However, it does make marking calendar time a bit awkward!

What would happen if we simply ignored the extra 0.24219 rotation at the end of the year, and simply defined a calendar year to always be 365.0 days long? The calendar is basically a charting of the Earth's progress around the Sun. If we ignore the extra bit at the end of each year, then with every passing year, the calendar date lags a little more behind the true position of Earth around the Sun. In a few centuries, Winter will begin in September!

In fact, it used to be that all years were defined to have 365.0 days, and the calendar “drifted” away from the true seasons as a result. In the year 46 BCE, Julius Caeser established the Julian Calendar, which implemented the world's first leap years: He decreed that every 4th year would be 366 days long, so that a year was 365.25 days long, on average. This basically solved the calendar drift problem.

However, the problem wasn't completely solved by the Julian calendar, because a tropical year isn't 365.25 days long; it's 365.24219 days long! You still have a calendar drift problem, it just takes many centuries to become noticeable. And so, in 1582, Pope Gregory XIII instituted the Gregorian calendar, which was largely the same as the Julian Calendar, with one more trick added for leap years: even Century years (those ending with the digits “00”) are only leap years if they are divisible by 400. So, the years 1700, 1800, and 1900 were not leap years (though they would have been under the Julian Calendar), whereas the year 2000 was a leap year. This change makes the average length of a year 365.2425 days. So, there is still a tiny calendar drift, but it amounts to an error of only 3 days in 10,000 years! The Gregorian calendar is still used as a standard calendar throughout most of the world.

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SECTION 11

Could you repeat that? I wasn't listening. Thanks.

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You can't ride home on a bowl of goat.
I've always said that.

AzCards21

Ingenious!!

maddogkf

But do they get paid for the 10 days they missed?

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AzCards21

No, They count as ten of your vacation days. But since you didn't really take the time off we don't have to pay you. No pay and no more vacation time left.

Get back to work slacker!

Ryanwb

Stupid Romans...and their noses