Overview:How big is the universe? If it began with the Big Bang, will it also have an end? Is there life beyond our planet? Questions like these inspired the launch of Voyager I in 1977 and have driven innovative space research and exploration ever since. Trace ground-breaking discoveries that have transformed our picture of the universe, from an age when we knew of no planets beyond our solar system, to today, when we have evidence of thousands and estimate trillions more. And follow the teams trying to solve two of the biggest mysteries in cosmology today: What are dark matter and dark energy?