All the planets, which I have discussed above, have physical and visual existence. But Rahu and Ketu have no physical shape. These are the imaginary points in the sky. But even then, Rahu is considered most powerful and has been allotted the status of a planet by our Rishis and seers. Mostly, Rahu confers malefic effect. He is considered a dirty planet indicating laziness, filthiness, delays and hurdles. He stays for 18 months in a zodiac sign.
In Hindu mythology there is an interesting fiction that describes how Rahu and Ketu came into existence. Once both, the gods and the demons agreed to form an alliance to produce nectar that could give them immortality. Nectar was to be obtained by churning the ocean. In the process, nectar was churned out. When the nectar was being served to the gods, a demon, disguised as a god, and sat between the Sun and the Moon in an attempt to acquire the nectar. The demon was recognized by the Sun and the Moon who complained of the demon to Lord Vishnu. Lord Vishnu immediately severed his head from his chakra. But the demon had already consumed enough nectar to make him immortal. The head of the demon, known as Rahu, became immortal. And the remaining corpse of the demon was known as Ketu. Ever since, Rahu and Ketu became the strong enemy of Sun and Moon. Sun and Moon eclipses occur due to Rahu and Ketu who swallow up Sun and Moon when they come near to them. In this way Rahu and Ketu take their revenge from Sun and Moon.
In Vedic astrology Rahu and Ketu are known as two invisible planets and they are strong enemies of the Sun and the Moon. Rahu and Ketu are actually the astronomical points in the sky respectively called the north and south lunar nodes. The places of intersection where the Moon`s path meet the Sun`s path is known as North Lunar Node and South Lunar Node respectively. Thus, the relation of Rahu and Ketu with Sun and Moon has been described through the language of symbol in Hindu mythology.
Rahu is a powerful and malefic planet. This is a favorable planet of the politicians. He gives them great opportunity and power to rise in the politics through any means fair or unfair. He also rules over thieves, jail, magicians, snake, poison and isolated places etc. Rahu has also the power to confer sudden wealth.
Being a shadow planet, Rahu has not been allotted any Zodiac Sign. Even then, Rahu exalts in Taurus Sign. If placed negative in a horoscope, he can create confusion, depression and emotional imbalances. On the other hand, he also has the power to make a person wealthy and popular.
Rahu professions: Rahu is a legendary master of deception who signifies cheaters, GAMBLING, LOTTREY BUSINESS, CAREER IN FOREIGN, pleasure seekers, operators in foreign lands, drug dealers, poison dealers, insincere & immoral acts,etc.
Rahu diseases: It gives suicidal tendencies, fears, phobias, poisonous bites, murder, theft, imprisonment, and diseases like cholera, dysentery, skin diseases, swelling of the uterus, and constipation.
Rahu Signs: Friendly signs are Gemini, Virgo, Libra, Sagittarius, and Pisces. Cancer and Leo are its enemy signs. Mercury, Venus, and Saturn are friendly planets. Rahu is an enemy of Sun, Moon, and Mars. Rahu gives auspicious results in Taurus and Libra. Rahu is capable of giving power when rightly posited or exalted, and it gives fame, success in politics, money, and physical beauty (i.e., attraction).
Rahu behaves like saturn: Rahu is regarded as similar to Saturn in its effect. Smoky blue is its color, instinctual and animalistic its nature. Rahu is interested only in achieving all that gives pleasure, and even if it achieves all it wants, it is never satisfied (which is true of our animalistic nature). Although Rahu rules no sign of the zodiac, the zodiacal sign Virgo is its sign. Virgo is in fact assigned to Mercury, but Rahu being akin to Saturn and Mercury being a friend of Saturn, Rahu thus has authority over Virgo.
Rahu god of chemical industry: Rahu governs all sorts of poisonous chemicals like fertilizers, pesticides, and disinfectants that are in use in the present times. It also governs all the substances with a strong pungent smell like the sulphur-dioxide gas. In other words Rahu has a role to play whenever a poisonous substance is involved. There is no equal to Rahu when it comes to giving Upliftment in Name and Fame , Sudden Luck Gambling, which is probably the reason why Western astrologers regard it as the greatest benefic force.
The gemstone associated with Rahu is a honey colored hessonite (Gomed). Its element is air and direction is south-west. Rahu reaches full maturity at age 42. The Puranas describe Rahu as half-bodied, born of a lioness, snakelike, having a huge body and being extraordinarily powerful. The Skanda Purana says that Rahu is instrumental in strengthening ones power and converting even an enemy into a friend. The effect of snakebite is removed by his grace. The lunar and solar eclipses are attributed to Rahu and Ketu. Rahu and Ketu stay 1 1/2 years in each Graha.
Rahu is the strongest enemy of Sun and Moon. There is much lore and mystery surround the Moon’s Nodes in Vedic myth, and they are considered of paramount importance in chart interpretation. In fact, in assessing planetary power, the only Graha that is more powerful than the Sun is Rahu, the North Node of the Moon, because of his ability to swallow the Sun during a total solar eclipse.