According to Puranas, the birth of Rahu and Ketu dates back to earliest of times.‘Samudra Manthan’ is regarded as one of the most important events in the history of Hindu civilization. Following which, Solar and Lunar eclipse are also associated with ‘Samudra Manthan’. When the ocean was churned by the Asuras and Devas, ‘Amrit’ was produced. This Amrit was stolen by Asuras and to obtain the Amrit, Lord Vishnu took incarnation in the form of a beautiful damsel ‘Mohini’ and tried to please and distract the demons. On receiving the Amrit, Mohini came to Devas to distribute it to them.
‘Svarbhanu’, one of the asuras changed his appearance to a deva to obtain some portion of the Amrit. However, Surya (Sun) and the Chandra (Moon) realized that Svarbhanu was an Asura and not one of the devas. Knowing this, Lord Vishnu severed Svarbhanu’s head with his discus, the Sudarshan Charka.
However, even though his head and body became separated, they still remained immortal as the separate entity because before his head was served, he managed to drink a drop of the nectar from the Amrit. The Head is known as Rahu and the headless body is the Ketu. Since then Rahu and Ketu constantly chase the Sun and the Moon for revenge as they are the cause of separating the head and body of the Asura Rahu. It is a popular belief that when they succeed catching Sun and Moon they swallow them causing Solar or Lunar eclipse but they can’t hold them for long and Sun and Moon emerge again intact as they also had nectar and are immortal.
Scientifically, Rahu and Ketu denote the two points of intersection of the paths of the Sun and the Moon as they move around the celestial sphere. Therefore, Rahu and Ketu are respectively called the North and the South Lunar nodes. Sometimes when the moon passes these nodes, it is aligned perfectly between the earth and the sun to create eclipses.
The fact that eclipses occur when Sun and Moon are at one of these points gives rise to the myth of the swallowing of the Sun. They transit in retrograde motion (in opposite direction to all other planets), hence they are not stationary. In Hindu astrology (Jyotish-Shastra), these cycles of Rahu and Ketu are well known, but their association with eclipses served to make the characters Rahu and Ketu relatively unknown, hidden and dark.
Rahu and Ketu are considered as two strong planets as per the principles of Vedic Astrology, although, astronomically, they do not exist. Since Rahu and Ketu are believed to have a strong impact on our lives, they are a crucial part of Jyotish Shastra and are denoted as mathematical points while making calculations in Vedic Astrology. The general explanation is that Sun represents body whereas Moon represents mind, hence, these incision points strongly affects the energies of these two parts of the bodies.
Generally, astrology mentions that Rahu represents indulgence. Some of its negative effects are Mental illnesses, theft, losses, the death of family members, legal hassles, etc. It also represents diseases such as leprosy, skin diseases, breathing problems, ulcers, etc. Rahu is also behind the instant success or failure of a person. However, if Rahu is well placed, it can bestow the native with courage and fame. Simultaneously, the negative effects of Ketu can cause diseases related to lungs, ear problems, brain disorders, problems in the intestine, etc. It represents mystic activities, wounds, sufferings, bad company, false pride, etc. Ketu also stands for moksha, sudden gains, interest in philosophical pursuits, spiritual pursuits, etc.
There are lots of dos and don’ts due to the positions of Rahu and Ketu. Thus, with each problem of planetary effects in our lives, Vedic Astrology (Jyotish Shastra) promises to have convenient remedies.