Natal Jupiter is the sign where your Jupiter was placed during birth time, and from there other houses are calculated clock-wise.
If you were born with Jupiter in Sagittarius, then your natal house is Sagittarius (Dhanus Rasi) and during transit, Jupiter forming conjunction (in Sagittarius), sextile (aspect of 60° which are Libra and Aquarius in this case), square (aspect of 90° which are Pisces and Virgo here), trine (aspect of 120° which are Aries and Leo here), opposition (aspect of 180° which is Gemini here) are discussed in this article.
Conjunction is transiting through same sign as in birth chart, sextile is transiting 3rd or 11th house, trine is transiting 5th or 9th house, opposition is transiting 7th house from natal sign.
Transit Jupiter conjunct Natal Jupiter: An increased stress on optimism, morality and self confidence are the key notes of this transit. The native becomes wiser because of change in his psyche. He now understand the world in a more mature and broader sense. The native may not become materialistically rich now. There may be educational opportunities present before the native to travel and broaden his base. The native has to be careful in business expansion. If Jupiter is afflicted in transit then out of capacity commitments and lavish expenditures may create problems.
Transit Jupiter Sextile Natal Jupiter: Ideas about educational, cultural and religious matters are the key notes of this transit. This is good time for learning, education and self awareness studies. A good time to deal with persons in power and authority and get ideas and plans introduced for consideration. A good transit for business negotiations and expansion and cordial relations with neighbors and siblings.
Transit Jupiter Square Natal Jupiter: Suspicion and conflict over educational and cultural beliefs and lavish expenditures are the key notes of this transit. The native is ego inflated and tends to be over loaded with work and responsibilities. The native is hypocritical now and should refrain from quick get rich schemes. Stomach and health are upset due to over eating and drinking. Almost all activities are non-productive now.
Transit Jupiter Trine Natal Jupiter: Intellectual attachment to philosophy, culture, education and travel characterize this transit. The native is optimistic and positive to execute his plans. The native tends to expand his knowledge by exchange of educational and ethical values. The native is intellectually aware of the needs and demands of the family members. The native tends to develop intellectual relations with any thing foreign. The native may be well off now in his profession with new initiative in desired line of thought.
Transit Jupiter opposition Natal Jupiter: Over confidence, insincere approach and extravagance are the key notes of this transit. The native has a tendency to take too much for granted and hypocrisy. There may be disagreements over educational and religious beliefs. This is a period of dissatisfaction with authorities as they can misinterpret one’s point of views. Care and restraint are required now for advantage. This transit is unfavorable for chance games and quick get rich schemes due to false over confidence. Travelling may prove costly without desired results now.