I agree Simon. How often in mathematics are things simplified by fixing your frame of reference with a moving coordinate system.
In reality, a moving sun is what we observe. We se the sun also rises. This is what we see. I have presented this challenge to this list in the past. What evidence is there to a naked eye observer that we live in a heliocentric or geocentric world. Geocentric is where we are centered and what we observe. Fine the earth moves in many ways but what observations can you make without a telescope that shows the earth rotates around the sun. Ptolemy knew the equation of time and accounted for it. He also accounted for the retrograde motion of the outer planets, Mars, Jupiter and Saturn. His flawed mechanical model allowed a mathematical description for the place of the earth, sun, planets and stars in a geocentric model. Read his great book, the Almagest The information is in the details, not the dumbed down précis of précis. I give him due credit. Likewise Copernicus Galileo and Kepler for their different moving frame of reference. Naked eye observations provide only two abstruse lines of evidence for a heliocentric universe. These are the Foucault Pendulum and the percentage of meteors observed in the morning compared to the evening. Subtle evidence indeed. The crescent shape of the interior planets can only be explained with a heliocentric model. But these are telescopic, instrumental observations, at least one step removed from what we see with the naked eye. This was Galileo's problem. Other than his suspect new fangled telescope, there was no evidence to prove the sun was not the centre of the universe. This was not religious dogma. It was a question of science. How could he convince Simplicio and the cardinals that the earth moved. It just defied our human experience. My challenge to this list remains. What evidence can be determined from a sundial that the earth rotates? Regards, Roger Bailey From: Simon [illustratingshadows Sent: Tuesday, December 13, 2011 5:23 PM To: Jan Bielawski ; Bill O'Neill Cc: [email protected] Subject: Re: sundial Digest, Vol 72, Issue 11 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 -------------------------------------------------------------------------------- --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
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