Rahu is the North Node and Ketu is the South Node of the moon. As the story in the Rigveda goes, a demon serpent Swambaru tasted the nectar of immortality without Vishnu's permission and thus was sliced in half. However, since he was already immortal having drunk the nectar he was given the status of planets Rahu the head and Ketu the tail. They are eclipse points of the sun and moon that affect the electromagnetic grid on earth. They are points on the ecliptic where the Moon is in alignment with the Sun and the Earth. They indicate the precise point of the harmony with the three most important influences in our life- the Sun, the Earth and the Moon. This relationship plays an important part in the unfolding of individual consciousness.
Within the yoga and astrological tradition, Rahu and Ketu are commonly associated with the serpent. Rahu represents the serpent’s head, and Ketu represents the serpent’s body; as such they are equated with the ‘path of the serpent’ which is the spinal column which is Kudilani Shakti. Rahu represents karmic obsession within our life, whereas, Ketu can represent karmic past. As nodes of the moon, they indicate the spiritual journey within the mind in relation to karmic challenge and karmic opportunity. To explore this concept more, there are important facets that should be understood by every student of spirituality. While both Rahu and Ketu are viewed as planets, in reality, they are nodes of the moon and more correctly are seen as shadowy planets as opposed to visible planets, even though they operate and embody the shadow realms within our lives. In Vedic Astrology, the concept of the Soul's journey through different lifetimes is central to it. The final goal of the soul is to break this cycle of life and death. Like the beads on a necklace, various lifetimes are joined together to form a necklace, each life being different but interconnected by an invisible thread. The invisible thread is Rahu and Ketu. The purpose of the soul in this life is to act out his given Karma, destroy the illusions of the materialistic life and move towards the pursuit of self realization where the mind is still and at peace. The soul's journey in a particular life time and its connection with eternal life is indicated by the position of Rahu and Ketu. Ketu deals with the past Karma and Rahu with the future. Rahu Ketu are the personal eclipse points. Therefore they are areas where you need to work out your Karma, past as well as future. They are our Karmic responsibilities. We have to learn to look beyond the momentary darkness that Rahu Ketu represent. They highlight the negative side of our nature which we need to overcome to move towards the spiritual growth. They work psychologically, therefore it is hard to pin- point their effect. They are the axis of life which indicates the path of spiritual growth from past life ( Ketu) to the future (Rahu). Knowledge of both the past and present are needed for true understanding of life. The past shapes the personality we are now, the negative and the positive Karma we are going to experience. It shades our psyche to how we are going to tackle the present. The future is always uncertain therefore can seem like darkness and carry fear and uncertainty within it. We have to really come to terms with our past to be able to not get afraid of the future. Rahu is showing this direction, Ketu is sometime blocking due to our actions of the past. The signs Rahu and Ketu are owned by planets and are Karmic control and Karmic distribution planets. The houses they reside in your birth chart and where Rahu and Ketu are placed become your focus. For example, if your Rahu is in Cancer and Ketu in Capricorn, the moon is your Karmic distribution planet as it owns the sign of Cancer. Saturn will be your Karmic control planet as it controls Capricorn. Capricorn, a sign that represents the energy of practicality, organizing ability and seclusion, is a big part of the karmic energy that Ketu is manifesting. Cancer is a sign of deep sensitivity that needs to be open and receptive, with a love of family and home. This means that your karma is to let go of organizing and control and learn to be more sensitive and trust your feelings.