From: Alex Ferguson (abf@interzone.ucc.ie)
Date: Tue 15 Jul 1997 - 01:38:07 EEST
Some ad hoc comments on Steve Martin's Theoretical Celestophysics, though
not as thorough as I planned, and may yet return to do later...
> Unless I'm wrong, the actual lengths are not 159 and 135, they have 1/2's
> in there as well, because the Equinoxes fall at noon but the Solstices
> each fall at midnight.
Doesn't sound right, as the interval you're measuring is between _two_
Equinoxes, and hence falls at the same time of day on each. Besides,
135:159 _is_ the ratio you used elsewhere, just not the one you said
you were using...
> As for earthly astronomy applying, I am of the firm belief that as many
> physical processes in Glorantha as possible should correspond to apparent
> earthly phenomena.
The current score seems to be "not many"... ;-/
> > o Each successive day varies in length from the preceeding
> > by an equal amount (not true of earth at all).
> > (2m7s (and a bit), trivia fans.)
> Also correct, on both points. However, how _close_ is the correspondence
> at say, the latitudes of the United States?
The (lack of) correspondence is the same at all latitudes, only the
magnitude of the change varies, not the pattern. Basically, to a first
approximation, the earthly pattern is sinusoidal, not linear. I keep
meaning to do some back-of-envelope calculations on this basis, though
I also have grave doubts about the overhead-at-equinoxes assumption,
too...
> Close enough that most people would think the differences were the same?
Nope, I don't think so. The phrase "The nights are fair drawing in"
is common to the point of cliche' where I came from, anyway...
Certainly the difference would be flagrantly huge to anyone who studied
Solar Celestology.
> >In at least one place in _each_ of ES and GRoY, it gives at least as
> >unequivocably that the midsummer sun passes directly overhead, so I
> >don't know why you think this is so "clear".
> Where in Elder Secrets does it contradict this statement?
The map, for one thing.
> ES I am more wary of contradicting
That seems a hopeless objective, since ES is contradicted variously by
itself, GRoY, as well as common sense, and later Greg pronouncements
too, if memory serves. At this point, the exact quantity of
contradiction seems a minor matter...
> Of the Winter and Summer
> constellations, two are of great importance -- if my model is correct,
> Ice Palace is _always_ due north when it is visible, which seems
> appropriate, and the constellation called by the Doraddi Pamalt's Spear
> is always directly south, also appropriate.
This being so, might it not be better to hand-wave these constellations
in a similar way to the Jumpers, rather than assuming that some whole
patch of Sky must behave in the same way?
> Note that Stormgate/the Pit
> does not rotate, but it does rock north and south, indicating it is
> probably on this other Dome.
I have to say this Outer Dome idea makes me shudder. If I understand
it correctly, it implies that up to about 10% of the northern sky (the
portion at the horizon) is, on a nightly basis, almost completely
immobile, while the remainder of the sky rotates past it at its usual
considerable lick? One can almost imagine a visible "join" between the
two, and this awful grinding noise...
> >Indeed so. This also raises the question of whether the sun has the
> >same apparent speed across the sky all day, or if speeds up near the
> >zenith in winter, and slows down in summer. (That almost made sense for
> >a moment, though it made my head hurt thinking about it.)
> The apparent speed at the zenith and horizons, if present, is negligible.
> However, the Sun should move much slower in summer than winter (and
> Lightfore do the reverse), since it is covering the same distance in a
> much longer time period.
Much slower _across the Sky_, that is, and presumably conversely, faster
in the underworld, hence my thought of a gradual speed-change (otherwise,
Yelm must slam on the breaks at the horizon, decelerating infinitely
fast: good job that chariot has well-oiled breaks).
Slainte,
Alex.
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