Some database systems, including the Sybase database that later became Microsoft SQL Server, use 1/1/1753 00:00:00 +0000 as the start of their epoch. The reason why this is is that 1753 is the first year in the English calendar that is fully coordinated with the Gregorian calendar. The English calendar has 11 missing days that were skipped from September 2 to September 14 to convert from the Julian calendar to the Gregorian calendar.

The Julian calendar was used from the days of Julius Caesar and measures the year at 365.25 days per year. But over the course of centuries, The calendar drifted by about 1 day over 128 years. This is because the mean solar tropical year is actually 365.2422 days. In 1582, this drift from the tropical year accumulated to 10 days. This caused Pope Gregory XIII to try to fix the calendar and he sent a commission of astronomers to redesign the calendar. The motivations of the Roman Catholic Church there were also to celebrate religious observances at the correct time. In 1582, Catholic countries skipped 10 days.

Of course, this happened after the English reformation and a lot of folks called it “Papist time” in England. And this is why England didn’t adopt the Gregorian calendar until 170 years later. This is also why George Washington’s Birthday is in different forms. One was called “Old Style” (which is the old Julian Calendar), and we also have a date in “New Style,” which was 11 days later.

The Orthodox Church never adopted the Gregorian calendar by not recognizing the authority of the Pope. This is why Orthodox Christmas is later and Orthodox Easter is later. And the Russians didn’t change their calendar until after the October Revolution of October 25, 1917 (which happened on November 8th, 1917 in the rest of Europe because of the calendar drift!)

On Tue, Oct 27, 2026 at 20:19 Brian E. Lavender <brian@brie.com> wrote:

Quote from __Core Java, Volume II: Advanced Features, 13th Edition__

> Now let us turn from absolute time to human time. There are two kinds
> of human time in the Java API, local date/time and zoned time. Local
> date/time has a date and/or time of day, but no associated time zone
> information. An example of a local date is June 14, 1903 (the day on
> which Alonzo Church, inventor of the lambda calculus, was born). Since
> that date has neither a time of day nor time zone information, it does
> not correspond to a precise instant of time. In contrast, July 16, 1969,
> 09:32:00 EDT (the launch of Apollo 11) is a zoned date/time, representing
> a precise instant on the time line.

I thought that was interesting. So, the Epoch perhaps ought to be June 14, 1903?

Brian
--
Brian Lavender
https://www.brie.com/brian/

"There are two ways of constructing a software design. One way is to
make it so simple that there are obviously no deficiencies. And the other
way is to make it so complicated that there are no obvious deficiencies."

Professor C. A. R. Hoare
The 1980 Turing award lecture
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