The influences pertaining to the four cardinal directions and the four ordinal directions in Vastu can be attributed to the influences of the other planets upon the Earth. Knowledge of the influences of certain planets upon the eight directional areas of one's home or office, and subsequent orientation of different room functions, greatly enhances the harmony of the living space.
The Sun's auspicious influences are strongest in the east of the home. Rooms in the east or northeast are good for prayer, worship, or meditation. It is auspicious to respect the Sun in this manner, as the Vedas state that by worshipping the Sun one becomes blessed with good health. Viewing the main entrance from the inside of the home, the room and window on the right side are ruled by the male energy of the Sun and thus this space is good for male occupancy.
The Moon's influence is strongest in the northwest. By upholding the principles of Vastu in the northwest, one's fame and honor are enhanced, and relationships are benefitted. Viewing the main entrance from the inside, the left side room and window are ruled by the female energy of the Moon and is thus good for female occupancy. The Moon also rules the bathroom, water storage, cow shed, and travel.
The influence of Mars is in the south of the home. Mars does have some very inauspicious influences, but can give tremendous strength and wealth. This depends upon the arrangement of planets in one's astrological chart. Mars influences wealth for those with a well-placed southeast kitchen, as well as a correctly placed chimney and fireplace. Vastu defects in the south bring about losses and problems, but good Vastu in the south inspires religiosity, justice, strong discipline, and power.
The influence of Mercury is in the north of home. By maintaining good Vastu in the north, Mercury cultivates study, business, communication, and moral character. Mercury also rules the areas of the home which function as an entryway, office, veranda, and natural area.
The influence of Jupiter lies to the northeast of the home. By maintaining good Vastu in the northeast, Jupiter strengthens one's character, bestows respect, influences the room containing one's most valuable possessions, favors a children's bedroom in the northeast, and nurtures spiritual development.
The influence of Venus lies to the southeast of the home. By maintaining good Vastu in the southeast, Venus enhances fine speech and provides auspiciousness to seating places, living rooms, dining rooms, bedrooms, and women.
The influence of Saturn lies to the west of your home. Given a main entrance in the west of the home, Saturn influences inauspicious circumstances such as divorce, depression, uncontrolled sensual indulgence, and general delays. On the other hand, if good Vastu is maintained in the west (meaning the west is more closed than open), then Saturn fosters auspicious qualities such as popularity, scholarship, happiness, and good eating. In such a condition, Saturn bestows auspiciousness upon store rooms, eating, the garbage area, and the flow of energy between the front entrance and the back entrance.
The influence of Rahu and Ketu is unique to Vedic astrology. The auspicious influence of Ketu comes from the northeast, and the inauspicious influence of Rahu comes from the southwest. Maintaining good Vastu in the northeast means to have open land slanted downwards. Maintaining good Vastu in the southwest means to keep both the interior and exterior areas raised and blocked off. Viewing the main entrance from the outside, Rahu rules the right side and Ketu rules the left. By maintaining good Vastu, their combined influences provides protection all around the home. Also, Rahu rules the entire main entrance, large, dark rooms, and large doors. Ketu rules the exit or back entrance, bathrooms, along with cracked or broken walls.