From: "Nigel Price" 
Subject: (urth) Spoilers and spoil heaps for "Castaway"
Date: Fri, 7 Feb 2003 20:37:24 -0000

In answer to my question about the shorter *day* on the planet in the story
"Castaway", Charles Reed wrote:

>>So the answer to the question is that the
>>Earth in the story (assuming that it is Earth)
>>is spiraling into the sun along with Mercury
>>and Venus, therefore speeding up its rotation.

I didn't follow this explanation at all until I went back and reread the
story today while I was still awake and discovered it was the planet's
*year* that was half an hour shorter. Duh! Through not paying attention, I
thought that it was the *day* that was shortened, hence my question.

OK, now I've got that bit clear in my head, can I test my understanding of
Charles' explanation by asking whether the reason why the planet is getting
colder rather than hotter, even though it is getting closer to its star, is
because the star is cooling and expanding and therefore, at the risk of
tautology, not giving out as much heat?

When does the increase in temperature produced by the reducing orbital
radius and the closer proximity to the sun outweigh the decrease in
temperature produced by the star's cooling?

Not that it matters - just curious.

Nigel


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