Saturdays in the Tamil month of Puratasi (September – October) is considered highly auspicious and special prayers are offered to Lord Balaji, Navagrahas and Lord Shani or Sani Bhagvan. The popular belief is that Lord Venkateswara made his divine presence on the earth in this month and returned to Vaikunata also in the month. There is also a legend that Shani Dev loses his powers in Puratassi month and therefore cannot create any trouble. In 2010, Puratasi Saturday are on September 18, September 25, October 2, October 9, October 16.
Sage Narada, or Narad Muni, wanted to know how people can worship Lord Ventakeshwara after his departure to Vaikunta. Lord advised Sage Narada that he will bless devotees who fast on Puratasi Saturdays and pray to Him. He will also relieve hardship caused by Lord Shani during Puratasi month. In 2010, Puratasi month begins on September 17 and ends on October 17
Since Saturdays are free from the evil influences of Lord Shani Bhagvan, it is easy to please him on this day. It is also believed that Sani Dev loses his powers in Puratasi month and therefore he will not come in the way of prayers dedicated to Lord Balaji. Thus it is easy to get blessings from Lord Venkateswara in this month. People offer Ghee Lamp or Ellu Lamp to Lord Shani in this month.
Lord Shani creating trouble is mainly believed by people who give importance to astrology.
Lord Venkateswara devotees take only a single meal on Puratasi Saturdays. There are also devotees who observe complete fast on the day. On Saturdays, Naamum, the two feet symbol of Lord Vishnu’s feet, is drawn on the forehead by males and women opt for a red dot. Hymns dedicated to Lord Vishnu are chanted on Saturdays.