Re: Riemann geometry, chicken or the egg?

Hero schrieb:

Robert Israel schrieb:

....................................... Some Greeks did have a
heliocentric system, but the idea that the orbits were ellipses
seems not to have occurred to anybody before Kepler.


Wiki -german about Alexander Thom:
"Neben dem Maßsystem trug Thom auch zu einer tieferen Betrachtung der
Geometrie der megalithischen Steinkreise bei. Er klassifizierte sie in
sechs Typen: echte Kreise, Ellipsen, zwei Arten von eiförmigen Kreisen
und zwei Arten von abgeflachten Kreisen."
The megalithic astronomers thought about orbits, of course there is no
hint in this to a heliocentric system.

And more, an orbit with epicycles is not a circle.
And there is one problem for astronomers and calendar-makers:
count the days between of the four seasons between the equinoxes (day
and night with equal length) and the winter and summer solstice, this
does not divide the year into four equal parts. So, presumed sun is
moving on a circular orbit around earth, it should have different
speeds. So one will look for alternative orbits.
Hero

.

Relevant Pages

  • Re: Riemann geometry, chicken or the egg?
    ... but the idea that the orbits were ellipses ... Wiki -german about Alexander Thom: ... The megalithic astronomers thought about orbits, ... hint in this to a heliocentric system. ...
    (sci.math)
  • Re: Kepler digital
    ... The orbits of the planets are ellipses, ... Prev by Date: ...
    (sci.physics)