Astronomical facts about Rahu and Ketu
Astronomically (as per Hindu Astrology), 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. 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.

Rahu and Ketu in Hindu Mythology
The Rahu is the son of Viprachitti and his wife Simhika, the sister of Prahlada. the devotee of Lord Vishnu. Ketu is the dismembered body of which Rahu is the head. The demi gods or the Devas were losing their glory and power due to a curse by sage Durvasas and the king of Devas the mighty Indra has lost his kingdom, the heaven to Asuras or the devils.

The Devas approached supreme father, and creator or universe, Lord Brahma for help, who guided them to Lord Vishnu, the preserver of universe. Lord Vishnu made a plan and suggested Devas to approach the Asuras and ask them for their co operation in churning the mighty ocean to obtain amrita, the nectar of immortality, which Devas and Asuras can divide among themselves and can become immortal. The Devas approached Asuras who agreed as this task required combined efforts of both Devas and Asuras.

They started churning using Mount Mandara as a rod and the Serpent Vasuki as a rope. Lord Vishnu incarnated as a Tortoise to hold up the mountain on his back. As the churning of the ocean started several things energed as a result, starting with poison Halahala which threatened to destroy all the universe but Lord Shiva kept it in his throat, without swallowing it. Kamadhenu, the wish-fulfilling cow, celestial horse Ucchaishravas, Airavata, the celestial elephant, the Kausthubha gem, the Parijataka (wish-fulfilling tree), Apsaras, the beautiful celestials maids, Lakshmi, the goddess of prosperity, Varuni, the goddess of liquor appeared one by one. Finally Dhanvantari, the god of medicine, appeared holding the pot of amrita. The Asuras forcefully snatched it, and refused to give it to Devas.

Lord Vishnu then incarnated as Mohini, the enchantress, the most beautiful female form in the universe. Devas knew this plan and controlled themselves but the Asuras were overwhelmed with lust for her and agreed to her decision for distribution of nectar as per her rules. She asked all the Devas and Asuras to sit in a line and started distributing nectar first to Devas. Rahu disguised himself as one of the Devas and sat between the Sun and Moon gods, who recognized him and told Vishnu who was in the form of Mohini. Lord Vishnu severed Rahu's head with his discus, the sudarshan charka but not before he managed to drink a drop of the nectar and become immortal.

Thus his Head and Body become separate but both become immortal as separate entity due to nectar. The Head is known as Rahu and the headless body is the Ketu. Since then Rahu and Ketu constantly chase Sun and Moon for revenge for they are the cause of separating head and body of the devil Rahu. And when they succeed catching Sun and Moon they swallow them causing Solar or Lunar eclipse but they cant hold them for long and Sun and Moon emerges again intact as they also had nectar and are immortal.

Body parts, function and diseases governed by Rahu and Ketu
Rahu and Ketu dose not govern any body parts but will govern the body part as denoted by planet or planets with which they are in conjunction or in aspect. Rahu and Ketu governs all types of epidemics, insanity, skin diseases, poisoning of all types. Rahu acts like Saturn and Ketu like Mars thus all body parts and diseases governed by Saturn is also governed by Rahu and all body parts and diseases governed by Mars are also governed by Ketu.

Professions governed by the Rahu and Ketu
As Rahu acts like Saturn and Ketu like Mars, generally they rules the profession signified by these planets, but apart from this they signifies profession related to occult arts, magic. Rahu or Dragons Head or North Node represents, foreigners, foreign countries, foreign travel, engineering and the technical trades, gambling dens, the underworld and the bad elements in the society. Ketu or Dragons Tail or South Node represents technical trades, spiritual inclinations, superstitions and electronics.

The Mantras for Rahu:
Beej Mantra of Rahu:
Om Bhraam Bhreem Bhraum Sah Rahave Namah

The Rahu Stotra:
Ardha kaayam maha veeryam chandraditya vimardanam simhika garbha sambhutam tam Rahum pranamamy aham

Gayatri Mantra of Rahu:
Om naaka dhwajaaya vidmahae padma hastaaya dheemahi tanno raahu prachodayaat

The Mantras for Ketu:
Beej Mantra of Ketu:
Om Sraam Sreem Sraum Sah Ketave Nama

The Ketu Stotra:
Palasha puspa sangasham taraka graha mastakam raudram raudratmakam ghoram tam ketum pranamamyaham

Gayatri Mantra of Ketu:
Om aswadhwajaaya vidmahae soola hastaaya dheemahi tanno ketu prachodayaat

Remedies for Rahu if it is malefic in Horoscope.
1. Worshiping of Bhairava or Lord Shiva.
2. Recitation of Kalabhairav Asthakam.
3. Reciting of Rahu Mantras as mentioned above.
4. Charity: Donate blue clothes, blankets, urad dal (Horse Bean) or coconut on Saturdays to beggars.
5. Fasting: On Saturdays.
6. Pooja: Maha Kaal.
7. Wear seven mukhi (seven faced) Rudraksh.
8. Rudraksh: Wear Eight Mukhi (Eight Faced) Rudraksh.
10. Do not eat non-vegetarian food on Saturdays.
11. Do not consume alcohol on Saturdays.

(It is not necessary to perform all the listed remedies; you can choose few of them)

Remedies for Ketu if it is malefic in Horoscope.
1. Worshiping of Lord Ganesha.
2. Recitation of Ganesha Dwadasanama Stotra.
3. Reciting of Ketu Mantras as mentioned above.
4. Charity: Donate brown cloths, blanket, black mustard seeds to beggars and feed black dog on Tuesdays.
5. Fasting: On Tuesdays.
6. Pooja: Maha Kaal.
7. Wear nine mukhi (nine faced) Rudraksh.
8. Do not eat non-vegetarian food on Tuesdays.
9. Do not consume alcohol on Tuesdays.

(It is not necessary to perform all the listed remedies; you can choose few of them)

Details About Other Planets
Sun in Astrology, Moon in Astrology, Mercury in Astrology, Mars in Astrology, Jupiter in Astrology, Venus in Astrology and Saturn in Astrology