The wizard of days and time
Date: Thu, 4 Nov 93 16:33:18 PST
Subject: The wizard of days and time
[This is the basic stuff you need to know before you can even think about
understanding Daylight Savings Time. Return with us now to September 3rd,
1752 ... oops! (That's right, type "cal 9 1752" to the shell.) -psl]
From: email@example.com (Stephen Andrew Weinstein)
Subject: Re: sept 1752
1582 was the real date of this calendar change, except they also moved New
Year's Day from March to January at the same time, which switched the year
The first calendars were based on a cycle of moon phases constituting a
year. Because there are only 354 or so days in 12 lunar cycles, this
calendar is now several months off from reality. This is why Ramadan
(the Islamic fast month) does not always occur at the same time of year.
The first solar calendar was a Egyptian one that had 360 days. They defined
a degree as the distance the Earth moved in a day. Even though we know now
that the earth does not complete a circle in 360 days, we still define a
degree as 1/360 of a circle.
The original 365-day calendar had no leap year days, but got out of synch
with the seasons so Julius Caesar instituted them and named the new calendar
the Julian calendar after himself. It had one Feb. 29 every four years,
i.e. 100 leap years per 400 years.
However, it turned out that a year was only 365.2425 days long, not 365.25
as previously estimated, so there should be only 97 leap years per 400
years. Therefore, Pope Gregory passed a rule that the first year of three
out of every four centuries would not be a leap year and announced that
certain days would be skipped (in 1582/3 only) to get the calendar and
planet back in synchronization. This calendar was named the Gregorian
calendar after him.
Only Catholic countries observed this. Being Protestant, the British waited
until the 18th century (i.e. 1700's) to announce the change retroactively.
This created a lot of confusion because everyone would have to change the
dates on any dated documents, so they created the terms "old style" and "new
style," where old style was the date that things that day were dated (i.e.
the date on the Julian Calendar) and new style was the official/Gregorian
date for dates between when the change was supposed to be retroactive to
(1582/3) and when it was announced. This is why George Washington (and
millions of others that we don't care about) has his birthday observed on
Feb. 22 (new style) even though he was born on Feb. 11 (old style).
The British had to skip 11 days, even though the Catholics only had to skip
10, because not only had the British not skipped the 10 days, they had also
incorrectly observed a leap year in 1700 so they were an additional day off
by the time they made the change.
As was earlier posted, the Russians did not make the change until after leap
years had been observed in 1800 and 1900. Therefore, they had to skip 13
The Greek (and maybe Russian) orthodox church(es) have never made the change.
As a result, they are still observing Christmas 13 days after everyone else,
when our calendars say it's January. Because the days of the week are not
different, they usually observe Easter, Good Friday, Ash Wednesday, etc.,
two weeks after everyone else, but sometimes only one week. Or maybe it's
sometimes a month, sometimes none, because Easter is supposed to be around
a full moon. I forget.
Some astronomers figured out that even with the new system, we will get off
in a few thousand years, because even the 365.2425 figure is slightly
Ironically, this happens to be about the same amount of time (i.e. a few
thousand years) that it will take for the calendar created by King Solomon
to get off. That calendar is lunar, but uses 13 months in some years, not
12 in all, in a 19 year cycle that has a total of 12 12 month years and 7
13 month years. It is used for setting the date of Rosh Hashona, etc.,
which is why such holidays are usually one to two weeks earlier than the
year before, but sometimes three weeks later than the year before.
Several years ago, someone proposed a calendar of 13 months of 28 days each
with either an extra week during 5 of every 28 years or with leap year day
and any one other day not assigned a day of the week. This would have the
advantage that any given day of the month would always come on the same day
of the week, during every month of every year. I don't know why this
proposal was rejected. I think it was because the leap week idea would
cause the seasons to flucuate slightly (like Rosh Hashona, etc., but to a
lesser degree) and the idea of giving some days no day of the week would
violate the commandment to observe the Sabbath every seventh day.
But you know that already.
© 1993 Peter Langston