Shani Trayodashi or Sani Trayodasi is an auspicious day for Hindus who perform Shani Puja. It is celebrated on Trayodashi day or the thirteenth lunar day which falls on Shanivar or Saturday. March 2010 is the auspicious month as two Shani Trayodasi fall during the month. The first Sani Trayodashi date in March 2010 is March 13 and the second is March 27th. Both the Shani Trayodashi fall during Chaitra month in North Indian traditional Hindu calendar whereas the former one is Falguna Krishna Trayodashi and the latter one is Chaitra Shukla Triodasi in Marathi, Gujarati, Kannada and Telugu calendars.
These two auspicious days also mark the last Shani Trayodasi in Virodhinama Samvatsar and the first Sani Triodasi in Vikruthinama Samvatsara in traditional Hindu calendar.
March 2010 Shani Trayodashi are also considered as Shani Pradosham. Shani Pradosh is the most auspicious day to worship Lord Shiva.
Devotees and believers of Shani dosham perform Shani dosha puja and Shani Shanti puja to please Sani. They do this puja for reduced or minimised effects of Shani dosha. Some people observe fast on the day of Shani Triodasi. Thailabishekam is one of the most popular pujas to worship Sani and to pacify the effects of Sani.