Search for extraterrestrial intelligence
Biology looks at how life developed on Earth and what type of environment scientists think is likely to support living forms. Previous Searches traces a brief history of searches, from Schiapparelli canals to NASA's SETI Project.
Any search must be preceded by an evaluation of the odds of finding a civilization with the capabilities of radio communication (Drake's equation) and by a choice of methodologies. This, as well as a summary of the current SETI Institute's research, are shown inCurrent Searches
How do we make contacts? looks at the way we (or "they") can establish contacts: interstellar space travel vs. radio signals. But what can we say to each other since we would speak two different languages (supposing "they" have a language...)? The odds to find an intelligent civilization, i.e. a civilization with the means and will to communicate with others using electromagnetic signals can range from zero (none to be fund) to one (there are enough civilizations out there that at least one will be in touch with us) depending to whom you ask.
Several critics also have argued that, if we take what happened on Earth as a model, intelligent life is not such a likely development of biological life. The reason is that it took a few billion years for life to diversify significantly and grow in complexity beyond the blue-green algae phase. Were not for the demise of the dinosaurs, which was due probably to an impact of a comet/meteorite with the Earth, the development of mammals would have been severely stunted or greatly retarded. So, we owe our own existence to a series of unlikely events. By all accounts, it seems pretty clear that there are no little green men on Mars or Venus. A somewhat more optimistic view is held about the chances of finding life, perhaps in some primitive form, on some other planets.
Inside the Solar System looks at the results of searches of forms of life within the Solar System. With the advent of cheap and reliable unmanned spacecrafts, this type of research has yielded surprising results.Outside the Solar System presents current research in the detection of extra-solar planets. The discovery of planets orbiting other stars has been the strongest boost to the argument of likelihood of existance of extra-solar life in a long while.
And if you indeed think that aliens have visited us, or even are among us, check out Aliens !.