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Re: Some more inconsistencies

From: Norm Wolcott <nwolcott2ster~at~gmail.com>
Date: Fri, 16 Jun 2006 13:58:23 -0400
To: "Jules Verne Forum" <jvf~at~gilead.org.il>

The following comment from the US Naval Observatory:

Greenwich Mean Time is a widely used historical term, but one that has been
used in several ways. Because of the ambiguity, its use is no longer
recommended in technical contexts.

"Prior to 1925, in astronomical and nautical almanacs, a day of Greenwich
Mean Time began at noon. This reckoning of Greenwich Mean Time is now called
Greenwich Mean Astronomical Time, and is no longer used. Persons using old
editions of the almanacs for historical research should be aware of the
previous convention."

The "day" apparently began when the sun passed over the zenith at Greenwich.



nwolcott2~at~post.harvard.edu
----- Original Message -----
From: <jcrovisier~at~free.fr>
To: "Jules Verne Forum" <jvf~at~Gilead.org.il>
Sent: Friday, June 16, 2006 10:18 AM
Subject: Re: Some more inconsistencies


>
> I wish to correct my preceding message. There is no error for the date(s)
> of the 1896 solar eclipse. This eclipse is referred to in the litterature
> either as the 8 August or the 9 August 1896 eclipse. The reason is the
> convention used by astronomers to count time and dates at that epoch. The
> "mean time" is counted from, and the change of date occurs at NOON, not at
> MIDNIGHT. With this convention, the eclipse occurred in Japan (where many
> observations were done) on 9 August, local date, whereas the date at Paris
> or Greenwich, used for the ephemeris, was then still 8 August. This may
be
> quite confusing, even to astronomers nowadays.
>
> Jacques Crovisier
>
> >
> > The 1896 eclipse indeed occurred on 8 August, not on 9 August as written
in
> > "The Fur Country". (But Camille Flammarion also specified "9 August"
for
> > the same eclipse in his "Astronomy Populaire".) As specified by Jules
> > Verne, the totality zone encompassed North Scandinavia and Siberia, but
not
> > North America (thus not in the same place). (I checked with the 1896
issue
> > of "Connaissance des Temps")
> >
> > Jacques Crovisier
> >
> >
>
>
Received on Fri 16 Jun 2006 - 21:02:30 IDT

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