Sun and Moon identified Swarabhanu as a demon and informed Lord Vishnu (Goddess Mohini) and instantly Lord Vishnu severed the head of Swarabhanu with cosmic Sudarshan Chakra. However, few drops of Amrita have gone into his mouth, hence two parts acquired immortality. The head is called Rahu and the tail Ketu. Simhika nurtured the head of the Swarbhanu and got a snake body. The severed body of Swarbhanu was nurtured by a Brahmin named Mini. Lord Vishnu granted a serpent head to the severed body of Swarbhanu and granted a boon that he will travel above Sun. Due to this Rahu and Ketu always treat Sun and Moon as their natural enemies and causes eclipses to Moon and Sun. Rahu makes Moon to Wax and Wane on daily basis and causes lunar eclipse. Ketu set to travel on the higher circute of Sun and causes solar eclipse.
(a) The Nodes of the Moon, viz., Rahu and Ketu, are not physical bodies but the points of intersection of the apparent lunar and solar orbital paths. Rahu is the ascending Node, Ketu descending. According to Brihat Parashar Hora Shastra, Chapter 47 verses 34-39.5:
(1) Rahu is exalted in Taurus and Ketu in Scorpio.
(2) Rahu owns Aquarius and Ketu Scorpio. Parashar says that some scholars are of the opinion that Rahu owns Virgo and Ketu Pisces. We can interpret this statement to mean that when Rahu is in Virgo and Ketu in Pisces, the Nodes will be taken to be well placed and should be disposed to give good results.
(3) Gemini is the mooltrikona sign of Rahu, and Sagittarius of Ketu.
(4) Thus, Rahu in Taurus, Gemini, Virgo and Aquarius shall be considered well placed. Similarly, Ketu in Scorpio, Sagittarius and Pisces should be considered well placed. This also shows that Rahu is well placed in the signs of Mercury, and Ketu is happy in the signs of Jupiter. Since Rahu is like Saturn and since Saturn and Mercury are friendly to each other this is quite natural. Similarly, since Ketu is like Mars and Mars and Jupiter are naturally friendly to each other, the relationship of Ketu with Jupiter is also understandable.
(b) Rahu in Scorpio and Pisces, and, Ketu in Taurus and Virgo should not be considered well placed. According to the Lai Kitab Rahu will give unfavourable results in the houses owned by Jupiter; and, Ketu will give adverse results in the houses owned by Mercury. Here the behaviour of Ketu is similar to Mars, since Mars too gives adverse results in the signs of Mercury; but it cannot be so said for Rahu since Saturn and Rahu are similar but Saturn gives good results in the signs of Jupiter.
(c) Jatakabharnam in Chapter on Cancellation of Combinations for Adversity verse 4 states that Rahu in the III, VI or XI house with the aspect of a naturally beneficial planet removes all indications of adversity in a birth chart. According to verse 8 of this Chapter, Rahu placed in Aries, Taurus or Cancer in the ascendant in a birth chart has similar effect. According to Jatakabharnam Chapter on Cancellation of Combinations for Adversity verse 9 Ketu in the VI or XI house in Capricorn, Aquarius or Pisces shall be beneficial.
(d) Rahu in the III, VI, XI, an angular or a triangular house will give positive general signification results. The results will be negative if it is placed in the VIII or XII house without association with or aspect of a naturally beneficial planet. The placement of Rahu in the VIII or XII house from the ascendant is not always found to give adverse results but it is a pointer to a possibility and should always alert the astrologer to go deeper and satisfy himself with respect to the results that Rahu may give.
(e) Ketu in the III, VI, XI, an angular or a triangular house will give positive general signification results. The results will be negative if it is placed in the VIII or XII house without association with or aspect of a naturally beneficial planet. When Ketu is placed in the II, VIII or the XII house, it may cause problems to the family of the individual or may make the individual lose his liberty in its major-period. As in the case of Rahu, the location of Ketu in the II, VIII or XII house may not always give adverse results, but a deeper analysis of such a Ketu is called for.
(f) The Nodes in their beneficial signs (exaltation, ownership, Virgo for Rahu and Pisces for Ketu, or mooltrikona) will give positive general signification results in their major-periods.
(g) In Chapter 34 verse 16 of Brihat Parashar hora Shastra the sage has described the predominant results that a Node is expected to give. He says that a Node will give results of the house that it occupies. The Node will also give results of a planet with which it is associated. The Laghu Parashari in Chapter on Definitions verse 13 also makes the same statement. It is observed that a Node gives results of (i) the house that it occupies, (ii) the owner of the house that it occupies and (iii) the planet that it is associated with, or is in sambandha with.
(h) A dispositor is the owner of the sign that a planet or Node occupies.
According to Uttar Kalamrita Chapter 6 verse 21, the quantum of the result in the period of a Node will depend on the strength of the dispositor of the Node. It will also depend on the strength of the planet with which the Node is, if at all, in sambandha.
(i) According to Brihat Parashar Hora Shastra, Chapter 50 verse 64, the period of a planet that owns a sign from which Rahu is placed in the tenth house will take the individual on a pilgrimage.
(j) According to Phal Deepika Chapter 20 verse 39, Rahu will take on the qualities and nature of the planet with which it is in association. It gives results according to the planet with which it is associated. Since Rahu by its inherent nature is malefic, it will vitiate the associating planet. The associated planet will take on the adverse qualities of Rahu. When Rahu and Jupiter are in association, if Jupiter is favorable in the chart it loses its ability to be good, and Rahu becomes favorable. A planet associated with Rahu will give adverse results at the end of its period. This principle may be extended to all planetary sambandhas with Rahu.
(k) According to Phalit Vikas of Ram Yatna Ojha, Rahu or Ketu alone in a house damages it. Phal Deepika qualifies it further. According to Chapter 20 verse 53, a Node when located in a sign of a naturally beneficial planet or in a favorable house will give good results in its sub-period if it is not in sambandha with any planet. Favourable houses for Rahu or Ketu have been stated above. In such a situation, the sub-period of a Yogakaraka planet in the major-period of a Node will be good. A Yogakaraka planet has been defined ahead (I) A Node, well placed in a triangle-free of the malefic influence of a naturally malefic planet, will invariably give excellent results in its sub-period in the major period of a naturally beneficial planet. The sub-period of a naturally beneficial planet in the major-period of such a Node will also be highly favorable.
(m) When a Node has sambandha with a planet, and both the planet and the Node have the relationship with a house, the Node will give the expected result relating to that house in its period, in preference over the planet.
(n) The nature of a Node will depend on the nature of the house that it occupies. This is the predominant consideration. A Node occupying the VIII or XII house is in normal circumstances unable to give good results. The nature will also depend on the nature of the dispositor and the sambandha that the Node may have with a planet.
(o) A Node in the II or VII house is generally considered dangerous, but according to Uttar Kalamrita, Chapter 6 verse 15, a Node so placed, when associated with or receiving aspect from the owner of the I, V or IX house, shall give long life and wealth.
(p) Rahu is a maraka planet for an individual born in Scorpio or Capricorn ascendant.
(q) The location of a Node in its sign of debilitation or in the VIII or XII house will make it give negative general signification results.
(r) At the time of analyzing the period of a Node, the analysis of its depositor should also be done.