The term for a scientist who studies the Earth's physical structure is "geologist." Geologists investigate different aspects of the Earth, including its rocks, minerals, landforms, and the processes that shape the planet over time. They utilize various tools and techniques, such as field studies, laboratory experiments, and remote sensing, to analyze geological phenomena. Their work is crucial for understanding natural resources, natural hazards, and environmental changes. Geologists play an essential role in fields such as environmental science, petroleum and mining industries, and studying climate change impacts on Earth's systems.