People fear Shani Dev because they are unaware of his nature and role in their life. He evaluates a person’s karma and dharma and accordingly functions in their life. When people suffer, they think they are being punished by shani dev through suffering. Actually there is no such thing. He just facilitates us to catch up with our karma - be it good or bad.
Shani Jayanti is marked as birth anniversary of Lord Shani. Shani Jayanti is also known as Shani Amavasya. Lord Shani is son of Lord Suryadev and rules planet Saturn and weekday Saturday. According to Astrology, Shani is referred to as Saturn which is known to have a strong influence upon people's life.