A geodesist is a scientist who studies the Earth's shape, gravitational field, and how these change over time. They use advanced technology and mathematical models to measure and analyze the Earth's surface, which is essential for mapping, navigation, and understanding natural phenomena. Geodesists often work with tools like GPS and satellites to gather data. Their work is crucial for various fields, including civil engineering, environmental science, and geophysics, as it helps in creating accurate maps and understanding the Earth's dynamics.