Astrobiology, once referred to as astrobiology, is associate degree knowledge domain scientific field involved with the origins, early evolution, distribution, and way forward for life within the universe. biological science considers the question of whether or not extraterrestrial life exists, and if it will, however humans will notice it. astrobiology is taken into account to own a slim scope restricted to go looking of life external to Earth, whereas subject field of biological science is wider and investigates the link between life and therefore the universe, which has the hunt for extraterrestrial life, however additionally includes the study of life on Earth, its origin, evolution and limits. once searching for life on alternative planets like Earth, some simplifying assumptions ar helpful to scale back the dimensions of the task of the astrobiologist. One is that the informed assumption that the overwhelming majority of life forms in our galaxy ar supported carbon chemistries, as ar all life forms on Earth.