For thousands of years, humankind thought that the Earth was the center of the universe. Thanks to our curiosity, imagination and urge to explore, we now know that planets like our Earth are not special in the cosmos. The Sun is just one ordinary star among hundreds of billions in our galaxy, the Milky Way....

The night sky, both beautiful and mysterious, has been the subject of campfire stories, ancient myths, and awe for as long as there have been people. A desire to comprehend the universe may well be humanity's oldest shared intellectual experience. Yet only recently have we truly begun to grasp our place in the vast cosmos....