Sky dome natterings

From: Peter Metcalfe <metcalph_at_voyager.co.nz>
Date: Sat, 21 Mar 1998 00:23:21 +1200 (NZST)


Trotsky:

Trotsky>>>They don't need to know when it's high noon *at the time*, they
>>>only need to know how long after dawn high noon is in particular parts
>>>of the world.

Me>>Then they wouldn't _need_ to ask someone in Boldhome, would they? The
>>phenonmenon would be readily apparent when they placed the gnomon on a
>>sundial.

> True, so long as they know that things are different elsewhere in the
>world than they are where they live, and that Boldhome is half-way between
>the eastern and western edges of the world (or thereabouts).

Why would they need to know things are different in other places? They can determine that since the local noon is off-centre then there must be some place where the noon is in the exact centre (remember they would know the noon is at dawn in the far east and at dusk in the far west). From simple trig, they can find out the radius of the sky dome. It is for this reason that I dislike the idea that an off-centre noon can be observed in the inner world.

>At any rate, my point
>is that *if* this is an accurate model for how the world works the
>calculation/experiment isn't all that hard to do.

And your point only holds _if_ there was a detectable solar parallax. I OTOH am arguing about whether _timezones_ could be detected (which is slightly different).

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