From: ram@zedat.fu-berlin.de   
      
   Charles Packer  wrote or quoted:   
   >On Thu, 8 Jan 2026 19:53:38 -0500 (EST), Scott Dorsey wrote:   
   >>There is a longstanding tradition of this.  Many people posited that it   
   >>was much easier to do the math by pretending that the earth actually   
   >>went around the sun instead if the other way around.  What got Galileo   
   >>in trouble was claming that it actually did.   
   >I hadn't heard this before. Could you identify one of these   
   >many people or cite a source for the assertion?   
      
     The heliocentric model basically goes back to Copernicus, a few   
     decades before Galileo, but Galileo's the one who really got   
     it out there. Before that, people had tossed around ideas that   
     kinda pointed in that direction, but the lack of parallax from   
     the fixed stars seemed to argue against it.   
      
     In the geocentric model, they used epicycles to explain the paths   
     planets seemed to take, but those weren't always seen as real   
     physical things - more like math tools to make the system work out.   
     (Also see the end of the quotation below for this.)   
      
     Even in the heliocentric setup, before Kepler came along with his   
     ellipses, you still needed epicycles to make the numbers line up.   
      
     Here's a quote with a source that doesn't mention any Greek ideas   
     about heliocentrism in the sense of "easier to do the math by   
     pretending that the earth actually went around the sun":   
      
   |This was so since after the Pythagorean school Greek astronomy became   
   |less purely speculative and more scientific. Eudoxus (409-336 B. C.)   
   |presented the first mathematical theory of celestial appearances. He   
   |tried to construct a theory of celestial motions out of uniform circu-   
   |lar motions which should agree with observations. He imagined the fixed   
   |stars to be on a vault of heaven; and the sun, moon and planets to be   
   |upon similar vaults or spheres, 26 revolving spheres in all, the motion   
   |of each planet being resolved into its components, and a separate sphere   
   |being assigned for each component motion. Callippus (330) increased the   
   |number of spheres to thirty-three. The real existence of the spheres was   
   |not suggested, but the idea was only a mathematical conception to facil-   
   |itate the construction of tables for predicting the places of the heav-   
   |enly bodies.   
   |   
   "The early history of the theory of eccentrics and epicycles"   
   (1917) - Noel Sargent.   
      
     This whole text ("The early history of . . .") doesn't show   
     any sign of heliocentrism being used as a calculation tool,   
     at least up until Copernicus.   
      
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