As 'Shani Dosham' (awful effects from Lord Shanis situation in an individual's horoscope) is well thought-out as an imperative facet in ones future aspects, Shani Puja is a propitious ceremony for believers. Shani yagya or homa is carried out on this day by those people who have the Saturn cycle or Shani cycle, properly known as 'Sade sathi'. A lot of people consider that Saturn cycle can be a cause for the dreadful part of their life. Appeasing Shani or getting hold of 'Shani shanti' is the most wanted consequence from such rituals.
Om shreem shanidevaya namo namaha!