(CNN) -- From a remote valley in Northern California, Jill Tarter is listening to the universe.
Jill Tarter at the Allen Telescope Array in California, which monitors radio signals for signs of alien life.
Her ears are 42 large and sophisticated radio telescopes, spread across several acres, that scan the cosmos for signals of extraterrestrial origin. If intelligent life forms do exist on other planets, and they try to contact us, Tarter will be among the first to know.
Are we citizens of Earth alone in the universe? It's a question that has long fascinated astronomers, sci-fi authors, kids with backyard telescopes and Hollywood executives who churn out spectacles about