Date: Tue, 12 Mar 2002 18:19:24 -0800
From: Michael Andre-Driussi 
Subject: (urth) Green's diameter, angular and otherwise

Another way to approach the Blue/Green conjunction is to determine the size
of Green in the sky of Blue, from its "usual" size to its greatest size at
closest approach.

For simplicity sake, let us assume that both Blue and Green have surface
gravities of 1 g.  More or less "twins" in separate orbits (and Green
having an orbital eccentricity that carries it out to a close approach with
Blue every x number of local years).

I was watching for details when I read before and I don't recall finding
any, other than "baneful eye."

OTOH, we have the happy case of an eyewitness who also sees Lune (maybe?)
and the Old Sun (definitely). The Old Sun (assumed before to have an
angular diamter of around 0.83 degrees) is "swollen" to his eyes, but iirc
he never says anything in comparison to Green's biggest size.

Using the Moon as a model.
        ORBIT      ANGULAR DIAMETER
MOON    240,000    0.52 degrees
LUNE    150,000    0.83 degrees
GREEN   105,000    1.18 degrees

So even a puny world like the Moon (diameter 2160 miles) would be more than
twice the size of the Moon in our sky when located at a distance attributed
to Green.

A twin planet would naturally be much bigger.

Based upon this, the Bluvian astronomer is quite likely to be waaaay off in
his estimate of the "closest approach" distance as being 35,000 leagues.

=mantis=


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