When is midnight? Nomenclature question

Paul Eggert eggert at CS.UCLA.EDU
Sun Apr 23 07:14:36 UTC 2006

"Dave Cantor" <Dave at Cantor.mv.com> writes:

> ... "midnight Tuesday".  Midnight _used_to_be_ a synonym for 2400
> hrs., the end of the day.

Yes, that's the usual meaning in English even now, I think.

> But we pretty much don't use 2400 hrs. any more, and "midnight" 
> has become a synonym, in some contexts, for 0000 hrs., the start 
> of the day.

Hmm, which contexts are these?  Do you have some quotes?

I ask because there is a lot of confusion around on this subject.
For example, <http://www.physics.nist.gov/News/Releases/questions.html>
says that railroads and airlines get around the 12:00 ambiguity by never
scheduling departures for either noon or midnight, but I once had a
printed airline ticket that said I left LAX at "1200N", meaning noon.

> Is anyone else concerned?  What should be done?  Who should do it?

It's a centuries-old problem, and I'm not sure we can do much about
it.  For more on this subject please see
<http://en.wikipedia.org/wiki/12-hour_clock> (not that it is
infallible either...).

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