How are astronomers approaching their search for life in the universe? What have we learned from the surge of exoplanets discoveries? How likely is it that Earth does not host the only life in the Universe? In this course we explore the field of astrobiology, an emerging multidisciplinary field. Progress in astrobiology is driven by telescopes on the ground and in space, and by new insights on how biology emerged on Earth and its diversity. The first detection of life beyond Earth might happen in the Solar System or by seeing biology’s alteration of an exoplanet’s atmosphere. A longshot approach is the search for extraterrestrial intelligence. The topics in this course range from the science of how exoplanets are detected, to the definition of habitability, to the chemistry that supports the argument that the ingredients for life are common in the universe. Astrobiology aims to answer one of the most profound questions we can ask in science: are we alone?