In Vedic Astrology, Shani means which moves slowly. Planet Saturn has been named after his nature. He takes two and a half year to cross a zodiac sign.
Saturn represents the longevity of an individual. Saturn is the planet of justice. A person under the influence of Saturn has to work hard in life. All the mining materials are ruled by him. Iron is his metal and black/blue is his colour. Saturn governs Capricorn and Aquarius zodiac signs. He is exalted in Libra and debilitated in Aries. His mooltrikona sign is Aquarius.
As per mythology Saturn is son of Lord Surya and his wife Chhaya (Shadow). Saturn has strained relations with his father. He represents old people. Saturn is considered a malefic planet in Astrology, but when placed in beneficial sign and bhava, he bestows an individual with great wealth and fame.
Sade-Sati :
Saturn, his transit in the 12th, the 1st and the 2nd house from the Moon position at birth has a special importance, it is called "Sade-Sati" (7 ½ years' Saturn) Saturn stays 2 ½ years on an average in a sign. So, in three signs combined, Saturn stays for 7 ½ and hence it is called ‘Sade-Sati’.
The period of Sade-Sati begins when Saturn entered the Zodiac sign immediately before the Sign of Moon at the time of the birth of the individual. That is, if the Moon sign (Ayamsha) at the time of birth of the person was Taurus, then the Sade-Sati begins when Planet Saturn enters Zodiac sign Aries.
This astrological period is much feared by people who give credence to Hindu Astrology. According to Vedic Astrology, this is a troublesome and worrying period for the person who is going through it. There may be various challenges in a one’s life
The results produced during Sade-Sati may be summarized as:
Quarrels and misunderstandings, implication, entanglement in litigation, failure of business, restlessness of mind, change of place, sickness among family member, death of children and mental worry.
One having good longevity can come under the sway of "7 ½ years' Saturn" thrice in his lifetime. During the first time, most of the above results will manifest; the second time, not some evil results will occur while during the third time the death of the native is invariably caused, unless the ruling Dasha does not warrant death.
Another related astrological transit of Planet Saturn (Shani) is the Dhaiyya (2.5 years), also known as Small Trouble (Small Panoti), and Ashtamshani or Kantakshani. This transit of Planet Saturn occurs when the Saturn is transiting through the fourth sign from the birth Moon sign (Kantak Shani), or from the eighth sign from the birth moon signs (Ashtamshani). Vedic Astrology says that these 2 are hazardous periods, though not as much as the Sade-Sati.