“Are we alone in the universe?” – this is one of the most fundamental human questions. For millennia, the only answers to this question were philosophical or theological; now scientists have begun to address this topic. Astrobiology, the study of life in the universe, draws upon the fields of biology, ecology, evolution, geology, astronomy, and cosmology in its search. In this course we will ask what life is, from a scientific perspective; examine the history and distribution of life on Earth; look for life among the inner rocky planets and outer icy moons of our solar system; hunt for planets beyond our solar system; and join in the Search for Extraterrestrial Intelligence (SETI). What will be the impacts on our society if and when we do discover life beyond the Earth?