Hi Ernst
In retrogression, planet's circular motion gets reversed. Is this reversed motion visible astronomically through telescope even for far away planets Jupiter and Saturn?
Thank you
Planets more so slow that we cannot notice any moment to moment changes in retro or direct. Day by day we will notice that the retro planet has moved back against the sky. The planet as it spins on its own axis, does not change of course. We can see planets rotate on their axis, especially jupiter which has about an 11 hour rotation, so in one night of 3 hour observing we can see the eye move from one side of jupiter to the other.
Okay thanks Ernst
In sidereal zodiac, retrogression dates of planets are quite different than tropical zodiac.
So, i was thinking looking at them astronomically could be a great proof of when planet is indeed reversing its rotation.
So, do they really reverse the rotation direction too ? And if we see them based on sidereal zodiac, then they wouldn't be seen as going back on those assumed retrogression dates?
No, retro dates are same whether tropical or sidereal. The do not reverse the rotation direction. THey really dont reverse anything, its just from the point of view of earth being on a different circle around the sun, it appears t hey are going retro. But that is just from the earth's point of view.