So, lets see what Jupiter can do in 3rd house without any conjunction or aspect from any other planet. 1st lets see what these 2 things represent --
Jupiter is the most benefic planet and it represents all the auspicious things like Knowledge, Wisdom, Law, Guru, Spirituality, Religion, Philosophy, Literature, Elderly People. For a girl, Jupiter also represents Husband.
3rd house - It is house of your communication skills, neighbours, short distance travels, younger siblings, marketing, announcements, collecting information, hobbies and skills, self-efforts, business, courage etc.
3rd house is house of communication and Jupiter is planet of Wisdom, so 1st of all this person's communications would be filled with wisdom. It is not necessary that they will be preachers or saints but whatever they do and say, will have some wise message involved within it. Jupiter here makes a person a very good businessman but in his 30s as it is one of Upachaya Houses, which grows with time. They also become very good writers and truthful journalists.
From 3rd house, Jupiter aspects the 7th house of marriage and blesses it. It gives a person very communicative spouse. Spouse would always have some wisdom to give to partner. Spouse gets involved in person's business.
Jupiter's next aspect goes to 9th house of religion, philosophy, pilgrimage and almost all the things which Jupiter represents. So, Jupiter's aspect further expands the quality of 9th house gradually and makes a person highly religious and philosophical.
Jupiter's last aspects goes to 11th house of gains, network circles, elder siblings. So, these people gain from their siblings, either elder or younger. They have large network circles and friends. They are very good with money matters.
Next - Jupiter in 4th house.
Vishal S Saxena - Astrologer