Can you tell me, what was the date 2,000 years ago starting from
September 15, 1996, and why [source preferred]?  Can you give me a
little time line around that time?  E.g.,

year -4, year -3, year -2, year -1, year 1, year 2, year 3?

This question is as straightforward as it looks.

Hello 8675309 (or perhaps Jenny? -- just a guess ;-) ),

As various pages agree, the Christian calendar from which we get B.C.
and A.D. (such as 1996 A.D.) does not include a year 0.

"Confusion Reigns Over Approach of The Millennium", by Randolph E.
Schmid (Feb. 27, 1999)
Associated Press
http://wire.ap.org/APpackages/20thcentury/centstories/022799confusion.html

"The year AD 2000"
National Maritime Museum
http://www.nmm.ac.uk/site/request/setTemplate:singlecontent/contentTypeA/conWebDoc/contentId/352

"Millennium and the Year 0" (01/04/99)
The Math Forum @ Drexel
http://mathforum.org/library/drmath/view/52565.html

The last of these pages helps to answer your question.  It notes: "To
find the time between an AD date and a BC date, you would add them and
subtract 1."

So, we can turn your question into an algebra problem, in which we
label the B.C. date "X":

2000 = 1996 + X - 1
2000 = 1995 + X
5 = X

X, the B.C. date, is 5.  Therefore, 2000 years before September 15,
1996 A.D. was September 15, 5 B.C.

You can think of it this way:  1995 years before September 15, 1996
A.D. was September 15, 1 A.D.  The year before that -- 1996 years
before September 15, 1996 A.D. -- was September 15, 1 B.C., since
there was no year 0.  And 4 years before September 15, 1 B.C. -- 2000
years before September 15, 1996 A.D. -- was September 15, 5 B.C.

The time line is just as you indicate in your question.  Stretching it
back a bit, it was:

... year -5, year -4, year -3, year -2, year -1, year 1, year 2, year
3 ...

I considered two potential problems with my calculation, and
determined that they are fortunately not problems.  First of all,
there are leap days in some years.  Secondly, and relatedly, there was
a changeover from the Julian to the Gregorian calendar, mentioned in
the National Maritime Museum page cited above.

As to the first issue, leap days are not a problem because most
everyone would agree that the year before September 15, 1996 was
September 15, 1995, and that the year before that was September 15,
1994, even though 1996 had a leap day and 1995 did not.  A year is a
year, whether or not it has a leap day.

As to the second issue, when the calendar changed from Julian to
Gregorian, our reckoning of the years prior to the switch also
changed.  A year before September 15, Year X was September 15, X - 1,
according to the Gregorian calendar; a 100 years before September 15,
Year X was September 15, Year X - 100, according to the Gregorian
calendar.  We are not interested in what the date would have been in
the old, replaced calendar, but what the date would have been
according to the Gregorian calendar.  Moreover, we are not interested
in whether a person at the time would have considered the date to be
September 15, 5 B.C. -- because, in fact, no one at the time would
have thought of it that way.  Rather, we want to know what the date
would have been if the same calendar as today -- the Gregorian
calendar -- had been in effect.

Whew!

- justaskscott


Search terms used on Google:

"year zero" bc ad
"year 0" bc ad

Splendid answer.   Concise, prompt, excellent value.

Btw, it's not Jenny; I'm male -- but just dig the song. :)