People have observed the stars for thousands of years, using them to find direction, note the passage of time, and to
express their values and traditions. As our technology has progressed, so has understanding of celestial objects and
events. Theories of the universe have developed over many centuries. Although to a casual observer celestial bodies
appeared to orbit a stationary Earth, scientific discoveries led us to the understanding that Earth is one planet that orbits
the Sun, a typical star in a vast and ancient universe. We now infer an origin and an age and evolution of the universe,
as we speculate about its future. As we look at Earth, we find clues to its origin and how it has changed through nearly
five billion years, as well as the evolution of life on Earth.