Why does Earth’s gravity vary from place to place?

Earth’s gravitational pull is not exactly the same everywhere. The planet is slightly flattened at the poles and bulges at the equator because of rotation, which changes the distance to Earth’s center. Mountains, dense rock bodies, and variations in crust thickness also affect local gravity a little. These differences are small, but they can be measured with precise instruments and matter in geophysics and satellite mapping. Scientists use gravity anomalies to study Earth’s interior and hidden structures.