Why does a day start at midnight? The bible refers to a day as "an
evening and a morning". At some time did a day start and end at
sunset? Through history, when did we start the next day at midnight?
Bill

Dear wildbill51-ga;

Thank you for allowing me to answer your interesting question. If you
are relying on Biblical history to support the notion that the day
ended in the evening as opposed to midnight, there is indeed some
tradition behind it. In the old Jewish tradition (which is largely how
the Old Testament was written) the days began and ended at sunset,
rather than at midnight. While the today?s contemporary Jewish
community recognizes the secular calendar day as ending and beginning
at midnight just as the rest of the world does, for customary and
traditional purposes the Jewish Calendar still recognizes the end of
the day at nightfall.

THE CALENDAR OF THE JEWISH PEOPLE
http://www.judaism.com/calendar/index.asp

Here is a good description of how the Jewish Community determines the
precise moment of dawn and dusk and how these times are defined:

COMPUTING HALACHIC TIMES ("ZMANIM")
http://www.hebrewcalendar.net/htdocs/zmanimhelp.en.html

Just as you suspected, the reference to day and night is not only
derived from God?s creation of the heavens and the earth in those
first few days, but by the need for a consistent, universal standard
by which all men, without the aid of a clock (which didn?t come along
until MUCH later) could tell what time it was simply by looking at the
sky:

?Midnight is not a distinguishable astronomic event. In the era before
the modern clock, a specific hour of the night could not be precisely
known, whereas an hour of the day was easily determined by sighting
the location of the sun. Thus, the day had to begin by precise, simple
and universally recognized standards. This meant that the day had to
be reckoned either from the beginning of night or the beginning of
day.

In Jewish time, the day begins with the onset of night (the appearance
of the stars) followed by the morning (which technically begins with
the appearance of the North Star). According to some Jewish teachers,
night and morning begin with sunset and sunrise respectively. For that
is how the Torah describes it: "And there was evening and there was
morning, the first day."

JEWISH TIME
http://www.aish.com/literacy/concepts/Jewish_Time.asp


I hope you find that my research exceeds your expectations. If you
have any questions about my research please post a clarification
request prior to rating the answer. Otherwise I welcome your rating
and your final comments and I look forward to working with you again
in the near future. Thank you for bringing your question to us.

Best regards;
Tutuzdad-ga ? Google Answers Researcher



INFORMATION SOURCES

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SEARCH TERMS USED:

JEWISH 

DAY

TIME

HOURS

SUNSET

NIGHTFALL

EVENING

MORNING

CALENDAR

BIBLICAL

TORAH

TALMUD

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Clarification of Answer by tutuzdad-ga on 19 Oct 2004 08:21 PDT

In answer to your question as to "Why a day starts at midnight", it is
generally accepted, though not proven (and historically disputed in
some circles), that the Romans were among the first to recognize that
day follows night and created their calendar to reflect the fact that
the setting sun has completed this transition half-way through the
night (midnight) and is therefore logically RISING thereafter. Herein
marks the point of the "new day" when the sun begins rising again,
even though daylight is not evident for approximatley 6 more hours.

Regards;
tutuzdad-ga

The answer was more than I thought I would get for the money. Some
time and thought went into the answer. It seams the Researcher knew
where I was coming from.
Thanks,
Bill

I suspect it was the Babylonians and that it probably had everything
to do with the closing times of pubs and clubs.

It isn't know exactly, but here is a good guess from an educated source:

"When did the roman-style counting (starting from dawn with 1) give
way to our modern style counting, starting at midnight (or midday)
with 0?  Perhaps when clocks were regulary synchronized with the sun. 
Noon/midday is the easiest and most accurate way of synchronizing
clocks with solar time, the basis for time until clocks were accurate
enough to track the Earth's irregularities."

http://homepage.mac.com/pete.boardman/24hourclock/history.html

This site gives a really good history of the clock, but admits that
historians disagree about many points due to the fact that no clocks
from earlier periods survived the centuries and there isn't a good
written history for clocks.