Happy Siva Ratri !
The Night of Siva occurs when the Moon is in between 156 and 168 degrees from the Sun ( Chaturdasi) in the lunar month of Maagha, in the Waning Moon Fortnight ( Krishna Paksha ).
This is a very sacred day for the Eternians.
Esoteric, scientifc aspects of this Grand Night, vIdeos and photos of the famous Aluva Siva Ratri at http://www.guruvayur4u.com/html/sivaratri.htm