Earth science--an essential early elementary topic--is the study of the planet we live on and the atmosphere around it. This set guides readers on a fun and detailed tour of Earth as well as the cosmos beyond. Do you know that the oldest fossils are 3.5 billion years old? Do you know that we rely on earthworms to keep Earth's soil healthy? Do you know that there's a kind of rock that floats in water? Learn more about these topics and many more inside these exciting guides to Earth and the universe it exists in.