NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: 0000 not 2400?
From: Derrick Young
Date: 2004 Oct 18, 16:31 -0400
From: Derrick Young
Date: 2004 Oct 18, 16:31 -0400
Gary,
I
started to dismiss your question as being frivolous - but it is not - as I was
reminded by my son's third grade class. I went in and talked for about an
hour on navigation, maps and charts, scales and time. I also brought
along a globe, sextant, compass, a couple of charts and other things so
that they could see what I was talking about.
Interesting thing is that one of the students asked that question - is 12
noon morning or afternoon? From a mathematical point of view, sounds like
the same question as asking if zero is positive or negative. In math,
you carry the sign from the direction that you are approaching - but in time
discussions, this is meaningless fluff.
There
are several different cultural definitions for when one day starts and another
ends. They include dawn to dawn, dusk to dusk, or as we have adopted,
00:00:00 to 23:59:00. Using this cultural bias, midnight is
considered to be the start of the day - I don't really want to get into the
merits of other cultural clocks and calendars here). If we
accept this definition (midnight being the start of the day) we could correctly
write the time as 00:00:00, 00:00:00 AM (redundant) or if you are
using a 12 hour clock, as 12:00:00 or 12:00:00 AM (again,
redundant).
Now to
the next part of the question - what about noon.
Dividing the day into two equal portions was done long before
Eratosthenes and his accurate measurement of the circumference of the
earth. We have carried this same concept forward even though we now start
our day at an arbitrary time (midnight), based on an arbitrary location (local
time meridian).
If the
morning and evening portions of the day are equal (both 12 hours) and we start
the morning at 00:00:00 (I have a hard time putting in the colons! Want to
write this as 000000!), then the afternoon (or more correctly evening) portion
of the day starts at 12:00:00, or on a 12 hour clock 12:00:00
PM.
What
you should come away from this is that this really depends on your cultural
definition as to when the day starts. In my family, midnight was always
the end of the day and noon was neither morning or afternoon. It was not
until I started learning something about navigation that I realized that was not
always the case.
Don't
know that I answered your question - may have just thrown more fuel on a
smoldering fire.
Enjoy,
derrick
