Why Saturday specifically
Saturday (Shanivar) is named directly for Shani, the planet Saturn, son of Surya, known in Hindu tradition as a strict but fair dispenser of karmic justice rather than a malevolent force. Worship on his own day is meant to ease the harshest effects of a difficult Shani period, such as Sade Sati or Dhaiya, rather than to seek favour beyond what's earned.
How the day is typically observed
Devotees visit a Shani temple, offer mustard oil, black sesame seeds and iron items, and recite the Shani Chalisa or the Shani Mool, Beej and Tantrokta mantras. Many also visit a Hanuman temple on Saturdays, since Hanuman devotion is widely believed to soften Shani's more difficult effects, as explained in our guide to Tuesday Hanuman Bhakti.
Shani Jayanti
Shani Jayanti, marking Shani's birth, falls on the Amavasya of the month of Jyeshtha and is observed with particular devotion, often including donations to the poor — a practice thought to please Shani, who values justice and fairness above ritual alone.
A day about earned outcomes
Unlike days built around seeking a specific blessing, Saturday's Shani worship is framed differently: less a request for good fortune, more an acknowledgment that discipline, patience and fair conduct through a difficult period are themselves the practice being asked for.