How did the Earth form? What's it made of, and how do we measure it? Learn all about our fascinating planet, including plate tectonics, weather, mountains and volcanoes, rocks and minerals, climate change, how fossils are made, and more. Plus, read about "known unknown" mysteries scientists are trying to solve, such as when we will deplete Earth's store of fossil fuels. And hear from Britannica Experts about their work in earth sciences including geology, hydrology, and paleontology, and their favorite things about studying our planet.