[geeks] You know you're an OpenVMS fanatic...

[David Cantrell]

On Fri, Aug 02, 2002 at 08:18:20PM -0400, dave at cca.org wrote:
> david at cantrell.org.uk writes:
> >On Fri, Aug 02, 2002 at 03:21:20PM -0400, Joshua D Boyd wrote:
> >> On Fri, Aug 02, 2002 at 03:15:23PM -0400, Ross Alexander wrote:
> >> > You know what happened on November 17, 1858.
> >> What happened?
> >Beginning of time.  VMS uses 1858-11-17T00:00:00Z as its epoch, which is, I
> >think, the day that the US Naval Observatory was opened.
> It's something more bizarre than that, and something only astronomers
> know about. I don't remember the exact details, but it's days since some
> ancient astronomical event, modulo a billion or something.

[google google google]

Oh yes, Modified Julian Day Zero.  The "real" Julian Day zero is
BC4713-11-24, which is the last time that the solar and lunar cycles *and*
the Roman tax system lined up.  The solar cycle is 28 years, the lunar
is 19 years, and the indiction is 15 years.  That particular intersection
of those three cycles was chosen by Scaliger because it preceded all (known)
history at the time he invented it.  Astronomers like to use the Modified
Julian Day (which is just the real Julian Day - 2400000) to avoid using
such bignums.  It also happens to be the base date of the US Naval
Observatory's ephemerides.

I don't know what an ephemerides is, but it sounds like it should be very
big and be made of gleaming, lovingly polished brass, and should make
satisfying *thunk* noises whenever bits of it move.

> >Because unlike DD/MM/YYYY and MM/DD/YYYY it is unambiguous.  VMS predates
> >ISO 8601 so we'll let them off for having their local standard varying
> >from the proper notation.
> I like YYYY-MM-DD because of endianness and sorting.

Yeah, I was using it because it was unambiguous and cos it sorts nicely well
before I heard of ISO 8601.

-- 
Lord Protector David Cantrell     |     http://www.cantrell.org.uk/david

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