On Sunday, January 14, 2018 at 8:45:49 AM UTC, Anders Eklöf wrote:
Gerald Kelleher wrote:



Direct/retrograde motions are for astronomers who can now distinguish how
we see the faster moving planets from the slower moving planets as seen
from a moving Earth.

Commom knowledge. But that's not what I asked about.
You talk about "direct/retrogrades resolution". What is that?


Not common knowledge before but it is now.

The illusory loops of the outer planets are converted into a simple perspective where the faster Earth overtaking the slower moving planets further from the Sun cause them to temporarily fall behind in view (direct/retrograde resolution).

https://apod.nasa.gov/apod/ap031216.html

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

The faster moving Venus and Mercury display actual loops with the Sun at the center -

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

Common knowledge - it is now !.

Taken from the perspective of the orbital plane , all observations of celestial objects when the Sun is out of view are to the left of the Sun as an evening appearance and to the right of the Sun (from the orbital plane perspective) -

https://www.youtube.com/watch?v=MdFrE7hWj0A


I would leave this last part alone and just enjoy the partitioning of direct/retrogrades from a moving Earth for the first time in 500 years as not even the original sun centered astronomers got that right -

"Now what is said here of Jupiter is to be understood of Saturn and Mars also. In Saturn these retrogressions are somewhat more frequent than in Jupiter, because its motion is slower than Jupiter's, so that the Earth overtakes it in a shorter time. In Mars they are rarer, its motion being faster than that of Jupiter, so that the Earth spends more time in catching up with it. Next, as to Venus and Mercury, whose circles are included within that of the Earth, stoppings and retrograde motions appear in them also, due not to any motion that really exists in them, but to the annual motion of the Earth. This is acutely demonstrated by Copernicus . . ." Galileo, 1632, Dialogue Concerning the Two Chief World Systems

Once you are shown how it is done it becomes common knowledge and that is fine. Unlike 500 years ago when Copernicus got it right with the slower moving outer planets, he spent 40 years trying to satisfy the antecedent Greek framework but in this era it is far, far worse with the proliferation of theorists who don't know the value of direct/retrogrades observations and their resolutions for even the outer planets.