On Wednesday, July 5, 2017 at 5:56:58 PM UTC+1, Mark Storkamp wrote:
In article ,
Gerald Kelleher wrote:

http://www.zam.fme.vutbr.cz/~druck/e...r/Tse1997uw2.p
ng

http://www.popastro.com/images/plane...%202010-Januar
y%202012.jpg

The images tell their own story of how we see the inner planets but the
eclipse marks a singular moment in time when Venus and Mercury are not
restricted to dawn or twilight appearances but are see as they truly are in
relation to the Sun and to the Earth.

Are you implying that when we see Venus and Mercury during dawn or
twilight, they do not appear as they truly are in relation to the Sun
and to the Earth?

There is nothing to imply as everything is obvious even if it is entirely new. If not exactly paint-by-numbers, the astronomical procedure is straightforward for those who can follow the imaging and graphics

The circuits of Venus and Mercury seen from a slower moving Earth are simple loops where the planets move from left to right of the Sun with familiar phase changes and size increases as they approach the orbit of the Earth -

http://www.popastro.com/images/plane...ary%202012.jpg

The change in direction of the inner planets to the background stars including apparent retrograde motion is simply that the inner planets reach their widest point seen from Earth before moving in front of the central Sun, until they move to their opposite widest point before turning back in behind the central Sun.

https://apod.nasa.gov/apod/image/011...2000_tezel.gif

Factoring in the Earth's orbital motion doesn't require relative speeds which dominate the outer planets as they fall temporarily behind in view (retrograde motion) as the faster Earth overtakes them, the slower motion of the Earth supplies an entirely different set of references and inputs for the faster moving Venus and Mercury.

First and foremost, the Earth orbital motion sets the Sun up as an external reference and that is why you go to the eclipse image -

http://www.zam.fme.vutbr.cz/~druck/e...Tse1997uw2.png

The background stars also move from left to right behind the Sun as the Earth travels through space or, as we see it without an eclipse, from an evening appearance to a morning appearance depending on where the Earth is in its orbit. The minor orbital input of the Earth is the delay by which Mercury and Venus reach their widest points seen from Earth but otherwise the inner planets complete their loops as would be expected ,at least as seen from the 1997 eclipse image above.

The original heliocentric astronomers had to satisfy the antecedent geocentric data which included the observed motion of the Sun through the constellations rather than the new approach which has the stars move behind a central Sun (due,of course,to the Earth's orbital motion) -

". . . the ancient hypotheses clearly fail to account for certain important matters. For example, they do not comprehend the causes of the numbers, extents and durations of the retrogradations and of their agreeing so well with the position and mean motion of the sun. Copernicus alone gives an explanation to those things that provoke astonishment among other astronomers, thus destroying the source of astonishment, which lies in the ignorance of the causes." Kepler , 1596, Mysterium Cosmographicum

There are some decent but deficient explanations for outer planetary retrogrades but none whatsoever for the inner planets and with good reason, at least up until presently. Knowing how to stop the Sun from moving in order to allow the inner planets accomplish their observed loops is the key to partitioning an astronomical division that didn't happen until this century.