Re: Cheesing the moon

From: Alex Ferguson <abf_at_cs.ucc.ie>
Date: Thu, 20 May 2004 22:06:40 +0100


On Thu, May 20, 2004 at 06:28:54PM +0300, Mikko Rintasaari wrote:
> Uh, ordinary? I'm suggesting that it looks the same from every place.
> Whether one is directly under the moon (in glamour) in Sartar or in Thrice
> Blessed, Rufelzas face is the same, and the shadow crosses her face at the
> same time. That doesn't sound all that ordinary to me.

I'm afraid it does to me. Ordinary in this world (apart from latitude and longitude effects, which are another matter entirely), ordinary in Glorantha. (Or at any rate, 'usual'.)  

> Come on, man. We had a table telling the phase of the moon in relation to
> the day of the week. No exceptions vere given. Simples explanations are
> still the best.

You mean in those books and games talking exclusively about Sartar and Prax? Your account might be the parsimonous generalisation, but no more than that.  

> If you refuse to see the problem, that's ok. The model given (for instance
> in the Reaching Moon magazine) with the searchlight, and it's explanation,
> leads to the moon behaving like I described. Never full and never empty,
> and always a half moon directly under it. Also, since the moon doesn't
> turn (it's the shadow that turns) Rufelza's face is different in every
> part of the empire.

No, you're not describing 'the model', you're describing what _you_ extrapolate from it using assumptions about 'physics' and 'optics' that are certainly inappropriate, and possibly invalid. I quote Nick Brooke on the topic (from his website):

: The Red Moon hangs motionless above the centre of the Lunar Empire, and
: slowly turns through her weekly cycle of phases. One face of the moon is
: bright red, the other is black. As the cycle progresses the red face
: wanes, replaced by darkness creeping around it. The darkness grows to
: cover half the moon, then three quarters, until the last crescent of red
: moonlight disappears. When the moon is dark (the Dying and Black
: phases), it can be seen only faintly by observers within the Glowline;
: it is no longer visible outside. It remains dark for two days, after
: which the red light creeps in again and waxes to full. An entire lunar
: cycle takes seven days and nights.

: This change of phases is not the same across all Glorantha: the Full
: Moon phase in Dragon Pass (which begins at sunset on Wildday) coincides : with the Black Moon in the north of the Empire.

That's not 'optics' or 'RW astronomy' or indeed 'geometric modelling', that's a description of what one _sees_.  

> I didn't claim it was, it's just the result of trying to get a "physics"
> model of how the moon vaxes and wanes,

But it isn't! I don't know if it was _intended_ as one, but as it cannot accurately be characterised as such, arguing against it on that basis requires a rather Inquisitional line of argument, if not to say guilt by association (without the association).

> instead of just accepting a simple mythic explanation "The moon's face
> is the same everywhere".

In this context, the word 'mythic' is really only conveying "Mikko likes it", just a 'physics' is mainly telling us "Mikko doesn't". Constancy is hardly an attribute of the mythology of the Moon, is it?  

> > I agree that 'bendy light' is a horrible account, but are you seriously
> > suggesting that Glorantha ought to simply not to have a horizon?
>
> Yup.

NIMG.  
> I think we could be dropped into a world with no horizon, and not
> notice it for a long, long time.

Unless you happen to live near an ocean, or in Prax, or Pent, or most of Pamaltela... And 'it won't bother much if you don't notice' is hardly a strong argument one way or the other -- that's as much to say it doesn't even matter mythically, and you're rejecting it one grounds of physics (i.e. that Bendy Light is ridiculous).

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