Pitra Dosh Puja

According to Hinduism, the souls of three preceding generations of one's ancestor reside in Pitru–Loka, a realm between heaven and earth. This realm is governed by Yama, the god of death, who takes the soul of a dying man from earth to Pitru–Loka. Hindus are expected to propitiate the ancestors(let the ancestors be in peace) in the first half, during the dark fortnight i.e Pitru Paksha, and let the soul of their ancestors reach Heaven from the Pitru-Loka.
When Sun and Rahu are in conjunction on the ninth, it is believed that Pitra Dosha Yoga is being formed. According to the scriptures, in whichever house the Sun and Rahu sit, all the fruits of that house are destroyed. There is such a defect in the horoscope of a person which can give all these sorrows together, this defect is known as Pitra Dosha.
The ninth house of the horoscope is called the house of religion, it is also the house of the father, if in any way the ninth house is afflicted by bad planets, it indicates that the wishes of the ancestors were left unfulfilled, which is a natural bad planet. They are called Sun, Mars, Shani and do their work in some ascendants, but Rahu and Ketu give their side effects in all the ascendants, the ninth house, the lord of the ninth house, the ninth house from the moon sign and the ninth house from the moon sign. If the owner is afflicted by Rahu or Ketu, then it is called Pitra Dosha. This type of person always lives in some kind of tension, his education is not completed, he keeps on yearning for livelihood, he is mentally or physically handicapped in some way or the other.
If in any way the ninth house or the owner of the ninth house is afflicted by Rahu or Ketu, then it becomes one hundred percent of the causes of Pitru Dosh.