Exobiology is the study of origins, of the distribution and evolution of life and of the structures and processes that are associated with it in the Universe (13). The word astrobiology indicates the same and is used in United States. Bioastronomy also refers to exobiology but with an astrophysicial point of view.

The scientific search for an extraterrestrial life is interesting because it deals with a lot of others scientific fields and it is rather recent. Doing a synthesis on this topic appears to be exciting and frustrating. Exciting because there are more and more discoveries, frustrating because this gives birth to contradictions. It's hard to be up-to-date on this topic when its actuality is rich of new elements. Moreover, the fact that scientific informations are made with data and references to other works makes it difficult to do a synthesis.
My goal is not to offer an exhaustive vision of this research field, but to bring a global image of the size of the related sectors and of the latest results, should they be positiv or negativ.

We will also look at four principal approaches used in exobiology :