Re: OT: Celestial maps

On Jan 12, 2008 1:23 PM, Mark J. Reed <markjreed@...> wrote:
> On Jan 12, 2008 10:50 AM, Eugene Oh <un.doing@...> wrote:
> > Is there a difference? I thought it'd be the same thing since
> > technically 0 would be midnight of Jan 1, 1 CE.
Oh, and we're not talking about a point in time, but a year.  The
whole year before 1 CE is 0 CE (a.k.a. 1 BCE), from January 1st
through December 31st.

Exactly when that year was depends on what you're talking about.  We
currently use the Gregorian calendar, and sometimes astronomers extend
it backwards well before its inception in 1582 to refer to past dates.
 But usually dates before then are given in the Julian calendar, which
is also a case of extending it backward in time.  It was established
in 45 BCE, but there's uncertainty around how it lined up until around
8CE, due to an error in the original leap year rule and later
correction.

If you extend the Gregorian calendar backwards, the day that comes out
as "January 1st, 0 CE" was a Saturday, 733,418 days or exactly 104,774
weeks ago today.   If you extend the Julian calendar backwards
instead, "January 1st, 0 CE" is the previous Thursday.  In either
case, the year that begins on that date is a leap year.

if you go by the calendar actually in use in Rome at the time, well,
obviously they wouldn't call the year 0 CE. :)   But the year that
corresponds to that, 753 AUC, according to the best scholarship
available to us, was not a leap year, and began on the Friday in
between the above two days.
--
Mark J. Reed <markjreed@...>

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