Today, 22 December 2011 is Pradosh Vrat. As it falls on Guruvar (Thursday), Brihaspathi or Guru Graha pradosha puja is observed. In some places, Guru graha shanti pujas are also observed along with Pradosha kaala Shiva vratham. It falls on Krishna Paksha Trayodasi in Margashirsha month as per Telugu, Kannada, Marathi & Gujarati calendars. And it is Krishna Paksha Trayodasi in Poush month in North Indian Hindi calendars.
Pradosha Kaala Shiva Puja time is between 4.30 to 6 in the evening. Pradosha Ashtakam is a popular prayer chanted during Pradosh Vrat.