Mythology can help us a lot in understanding the nature of Rahu and Ketu. Mythology is a set of stories that hides deep esoteric mysteries of life. This is true for all authentic mythology – Eastern and Western. Authentic mythology means mythology constructed by enlightened beings who have penetrated to the deepest secrets of life. They were called Rishis – the enlightened seers – in ancient India.
Some people think that myths are cock and bull stories. But that is not true. Myth doesn’t mean false. That is wrong understanding. Myths represent the deepest wisdom of a given culture.
Let me give you an example of this fact by answering this question on the nature of Rahu and Ketu. There are two shadow planets in Indian astrology called Rahu and Ketu. They are called the Moon’s North and South Nodes respectively in western astrology. In some other parts of the world, they are called the Dragon’s head and tail respectively. In the Indian mythology they are believed to be a demon called Swarbhanu who had participated in the churning of the ocean. Many things came out of the ocean one after the other. In the end, ‘amritam’ or nectar came out. According to mythology, anyone who drinks this nectar becomes immortal. The churning of the ocean was done by the gods and the demons together. The gods were worried that if the demons too drank the nectar, they would become unconquerable, and that would be too bad for the regulation of the Universe. So, they requested Lord Vishnu for help.
Vishnu took the form of a lovely lady called Mohini and started to distribute the nectar. The gods and the demons were sitting in two rows facing each other. Mohini was so beautiful that all the demons forgot themselves and started fantasizing about a life together with her. She was dancing tantalizingly and giving the nectar only to the gods, swaying seductively and passing by the demons, without giving them a drop.
This demon Swarbhanu was very smart. He understood the entire plot. He took the form of a god and sat between the Sun and the Moon – the two luminous gods. Mohini could not recognize the demon in time and as a result, Swarbhanu got a gulp of the nectar of immortality. The Sun and the Moon immediately shouted out in unison that Vishnu had given the nectar to a demon by mistake. Vishnu immediately cut the demon’s head with his divine disc. He threw the head of the demon towards the north and the rest of the body to the south. It is believed that ever since these two separated parts of the demon are circling the sky chasing each other so that they can unite but in vain. No matter how much they try, they remain 180 degrees apart from one another. In every birth chart, these two, Rahu or the demon’s head, and Ketu or the demon’s tail, sit 180 degrees away from each other.
Rahu and Ketu is considered as two strong planets as per the principles of Vedic Astrology. But astronomically, they do not exist. Since Rahu and Ketu are believed to have a strong impact on our lives, they are denoted as mathematical points while making calculations in Vedic Astrology.
When Moon moves from South to North in its orbit and crosses Sun’s path – the incision point is called Rahu or Dragon’s Head. When Moon transits towards South and crosses the Sun’s path – the incision point is called Ketu or Dragon’s Tail. This point is at 180 degree distance from the previously mentioned incision point (Rahu).
In Vedic Astrology, Rahu and Ketu are given high importance. But why? Why are these incision points considered so important? The general explanation is that Sun represents body whereas Moon represents mind and these incision points strongly affect the energies of these two planets.
Rahu and Ketu are not stationary. In a year, they move 19 degrees and 30 minutes which means that Rahu and Ketu take 18 years and 6 months to complete 1 round around Earth. These two planets transit in retrograde motion (in opposite direction to all other planets).