When we gaze into the peaceful, twinkling night sky, we see much the same vistas witnessed by our ancestors thousands of years ago. Yet centuries of scientific progress have so transformed our understanding that it cannot be said we share their same simplistic view. We now know that the world is not flat, that the sky is not a dome, that the stars are not pinholes through which flickering fires shine.
Many mysteries remain, of course. But with every year, new discoveries bring a better understanding of how our cosmos emerged, how it evolved and where it is going. Today we know that the stars are suns and that Earth is just one of billions of planets in our Milky Way galaxy. Scientists are racing to learn whether or not we are cosmically alone, looking for Earth-like planets and studying them for signs of life.