In a Horoscope, what does retrograde Jupiter mean?
This picture explains how we see a planet going retrograde from the earth?
This is just an illusion. A relative perspective. In fact, no physical planet moves in reverse motion. However, in Astrology we have accepted many phenomenons contrary to astronomical facts and we have built rules beyond heliocentric view. So, there is nothing wrong if the map of the sky (horoscope) shows a planet in retrograde motion. Ultimately all rules of astrology are based upon observation only.
Practically, during retrogression, a planet remains in the same sign for a longer duration. So whatever result we perceive for the planet in that sign will be prolonged.
What we may need to consider ?
The nature of the planet, is it benefic or malefic?
The nature of the sign the planet is passing through
Relationship of the planet with the particular sign. Is it friendly, own, moolatrikona, inimical, exaltation etc.
From the above we can see what will happen if the condition of the planet occupying the same sign is prolonged? Let us be very logical :
A benefic planet staying longer in friendly, own or exaltation sign will magnify the benefic results
A benefic planet if passing through inimical sign, debilitation etc. means, the benefic planet may continue giving weak results for a prolonged period.
A malefic planet staying longer in friendly, own or exaltation sign will magnify the malefic results
A malefic planet if passing through inimical sign, debilitation etc. means, the malefic planet may continue giving weak results for a prolonged period. Thus it could be a relief from the malefic influence.
Focusing on the question, Jupiter being a natural benefic planet we can assume that it will give good result for extended period of time if the retrogression happens in its friendly, own or exaltation sign.
But this may not be always true. Because we have to check significance of Jupiter on the basis of the particular subject under scrutiny. The subject matter and native’s horoscope will change the scene. Let us take an example :
If the native wants to influence the judiciary to get judgement in his favour in a pending case,
Jupiter’s retrogression in friendly, own or exaltation sign will not help because Jupiter will promote Justice over extended period.
Jupiter’s retrogression in inimical or debilitation sign may be helpful because Jupiter’s weakness over extended period may provide better opportunity to influence upon the merit of justice.
I know well that at least one logic given above is contrary to opinion of accepted classical books of astrology. Nonetheless, we need to promote Astro-Logic to make it more acceptable to the intellectuals and free it from the hearsay astrologers. Astrology has remained a developing subject over the centuries. We can see new observations and interpretations promoted by the seers like Parashara, Jaimini, Bhrigu etc.