Astronomical Studies on SETI

Search for extraterrestrial intelligence (SETI) is indeed a great challenge to astronomers since its method of communication, direction of propagation as well as spectral pattern are all unknown earlier. Due to all of these various restrictions, the problems have become complex and thus the science has become a 'hard science'. As galactic societies would be transitory, an obvious solution is an interstellar communication network, or type of library mostly consisting of automated systems to store the cumulative knowledge of vanished civilizations and thereby to communicate the knowledge through the galaxy. This is called 'interstellar internet', where the different automated systems act as network servers. Intercepting such signals is highly difficult and extremely complex. The article reviews the modern techniques and instruments for celestial search. Theories and hypothesis developed for investigating life in the universe including some exciting findings have been critically examined.