[whatwg] BC AD BCE CE trivia

WeBMartians webmartians at verizon.net
Tue Aug 28 17:41:31 PDT 2007

There is a disagreement between astronomers and historians about how to count the years preceding year one; astronomers count the BC
years astronomically. Thus, the year before the year 1 is the year 0, and the year preceding the latter is the year -1 (2 BC, 1 BC,
and one are, astronomically, -1, 0, and 1, respectively). The year which the historians call 585 BC is actually the year -584. The
astronomical counting of the negative years is the only one suitable for arithmetical purpose. For example, in the historical
practice of counting, the rule of divisibility by 4 revealing the Julian leap-years is no longer valid; these years are, 1 BC, 5 BC,
9 BC, 13 BC... In the astronomical sequence, however, these leap-years are called 0, -4, -8, -12..., and the rule of divisibility by
four subsists. In this system we can speak, for instance, of the solar eclipse of -1203-08-28 (twenty-eighth day of August in the
year 1204 BC), although at that remote time the Roman Empire was not yet founded and the month of August was still to be conceived!

Also, the (politically?) correct way to specify BC is "Before Common Era", while AD (Anno Domini) is now CE (Common Era).

A good reference is Astronomical Algorithms  by J. Meeus  and published by Willmann-Bell, Incorporated Post Office Box 35025,
Richmond, VA 23235.

Heck, according to the Mayan calendar, everything's kaput in five years anyway! (at least, I THINK we have five years)

From: whatwg-bounces at lists.whatwg.org [mailto:whatwg-bounces at lists.whatwg.org] On Behalf Of Krištof Želechovski
Sent: Tuesday, 2007 August 28 10:48
To: 'Rikkert Koppes'; whatwg at lists.whatwg.org
Subject: Re: [whatwg] (no subject)

I think arithmetic notation for dates B.C. is unintuitive and hard to understand (also because in terms of dates -1+1=1).  It would
be better to present a B.C. check box, or just say it aloud if dates A.D. are not expected.



-----Original Message-----
From: whatwg-bounces at lists.whatwg.org [mailto:whatwg-bounces at lists.whatwg.org] On Behalf Of Rikkert Koppes
Sent: Tuesday, August 28, 2007 10:39 AM
To: whatwg at lists.whatwg.org
Subject: [whatwg] (no subject)



- are negative years allowed (B.C.)? the datetime description tells me "four or more digits (0 to 9) representing the year" which
implies "no". use case: hystory questionary

Rikkert Koppes

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