On Friday, January 25, 2019 at 8:14:20 PM UTC, palsing wrote:
On Friday, January 25, 2019 at 4:37:02 AM UTC-8, Gerald Kelleher wrote:

If you want to believe Venus doesn't show a closed loop with the Sun at the centre then be my guest, this type of astronomy is not for everyone.

I never made that claim, Gerald, I only reminded you that apparent planetary motion with respect to the Sun is not the only perspective. In your case, it seems to be the case that apparent planetary motion with respect to the fixed stars is not for you... but I can assure you that it is still astronomy.

The people I respect are Galileo and the original Sun centred astronomers who never knew this perspective as they assigned the back and forth motions of Venus and Mercury as illusions caused by the Earth's orbital motion -

"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

These were great people who could rightly celebrate half a solution as the illusory loops of the slower moving planets are discerned against a fixed stellar background -

https://apod.nasa.gov/apod/ap181108.html

There is so much going on with the direct/retrogrades of the faster moving Venus and Mercury that only satellite footage could resolve their motions and ours around the Sun.