I was asked in a separate emial to expand on why one uses the sun rotates
around the earth. My reply was...
"If the student understands the various differing frames of reference, then
the frame of reference that simplifies the current need is the best one to use.
Were one to insist that the sun moves around the earth with no other
explanation, then you would have a point. That is, however, not what I teach,
nor the many other authors. Too many teachers complicate a simple issue. The
view to use is that which creates in the simplest manner the correct answer,
not one the teachers insists on using. And I believe this answers your original
question of why people still teach the sun moves around the earth."
As a PS, I wonder if the original question was concerned with the law of
primacy. If so, the pedantic view is valid. However all authors whose work I
have studied clearly explain the orbiting planets, and then state the simpler
way of viewing dial plate design is by assuming the sun orbits the earth. There
is no violation of the law of primacy in that case, and the student has an
easier time of things. Why rotate the dial plate and gnomon around a light
source, when rotating the light source alone will make the dial plate design
easier?
Simon
Simon Wheaton-Smith
www.illustratingshadows.com
Silver City, New Mexico W108.2 N32.75 and
Phoenix, Arizona, W112.1 N33.5
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