This is a branch of astronomy that examines the physics of the universe. Objects that are studied include galaxies, stars, planets--both in our solar system and out of the solar system. It deals with outerspace and cosmic background radiation, which is cited as evidence that the big bang occurred. The goals of this field are to understand our universe and to investigate how it was created. Another is to find planets suitable for life to develop and to search for other worlds and possible life. Scientists in this field have areas of expertise in physics including--quantum mechanics, relativity, nuclear and particle physics, electromagnetism, and others.