The following defines each planet by ascendant, its particular effects as lords of certain houses.The Sun, as ruler of house 3, shows Gemini's soul of curiosity, intellectual impulse and strong opinions, which can cause them to rely too much on their own thoughts and energies. It also shows their strong sense of friendship and tendency to form alliances, particularly for the working out of their ideas. It is inauspicious.
The Moon, as ruler of house 2, gives fluency of speech, good education and capacity to gain wealth. It endows Geminis with highly developed minds. Additionally, it indicates their great sensitivity and need for emotional nurturing as children. It is generally neutral.
Mars, as ruler of houses 6 and 11, is triply (by nature and by ruling two houses of injury) a planet of violence. Gemini's tend to suffer from accidents and injuries from their absent mindedness or through blindness generated by their own opinions or excessive idealism. They suffer from excessive activity, overexertion or hypersensitivity leading to nervous burnout. Mars is very inauspicious for them.
Mercury, as ruler of houses 1 and 4, indicates their close alignment of self and mind. While this gives directed mental powers, it can detract from objectivity in regard to the self. It can cause an overly self sensitive psychological nature. Any aspects to Mercury will triply affect the mind because the planet rules the self, the ascendant, the mind, and the fourth house and naturally indicates the intellect as well. Mercury is auspicious as the ascendant lord.
Jupiter, as ruler of houses 7 and 10, shows a strong will and idealism as well as a seeking of power and prestige in relationship. Geminis over express themselves in relationship, which can lead to dissipation and a diffusion of energy. Though generally inauspicious, it is mainly when weak by house, sign or aspect that Jupiter will give bad results.
Venus, as ruler of houses 5 and 12, is a planet of passion and luxury. It shows the strong artistic sense and wealth-giving power of Gemini but also its excessive sexuality that leads to loss or dissipation. Gemini types suffer from nervous stimulation and can become enervated through sex. On a higher level, Venus gives them creativity and intelligence and general good fortune. It is probably the most auspicious planet for the ascendant.
Saturn, as ruler of houses 8 and 9, can function as a spiritual planet, giving profound intelligence. It also shows the basic ambiguity and contradictions of Gemini types, which can destroy them. They get caught in the dualities of their own minds. Hence, Saturn becomes neutral in its function, though perhaps slightly auspicious (with its Mulatrikona sign Aquarius marking the ninth).
Venus and Mercury (ruling houses 4 and 5) together give Raja Yoga. Venus and Saturn (rulers of houses 5 and 9) give much success inlife. Mercury and Saturn (ruling houses 1 and 9) give spiritual awareness. Mars with Jupiter or the Sun (rulers of houses 6, 7 and 11) creates a disturbed or hyperactive mind, which may lead to difficulties or disasters.
As a mutable and air sign, planets for Gemini tend to scatter and diffuse their energy. Their action is often quick, premature, irregular and hard to predict. Though a good ascendant for the mind, it is not so good for long term success in the world and has a tendency towards disease and injury. In this computer age, Gemini has a new advantage, however, with their quick and abstract minds.