Meet NASA scientist Lynn Carter, who studies the geology of planetary surfaces, in this video adapted from NASA's Goddard Space Science Center. Carter describes how scientists learn about Earth by studying other planets and moons. Objects such as the Moon have older surfaces, which serve as a record of early solar system conditions, because they have not been subject to Earth's tectonic and erosive processes. Carter explains various aspects of her work, including image analysis, writing, field work, and the use of radar to penetrate through surfaces to see hidden features on Earth, Mars, and the Moon.