Figure 6-1 RIVUXG Earth’s Vital Statistics The planet symbol for Earth is ⊕. Other planets have different symbols; these are often used as shorthand for information about each world. For example, the mass of Earth is often denoted M_⊕. This figure provides information about Earth’s physical and orbital properties. Astronauts spend many hours watching our world as they orbit it. The image here gives you an idea of why they find it so fascinating.