We asked yesterday if the pull of gravity is the same everywhere on Earth. As many of you noted, the answer is no. This map of Earth's gravity field, based on airborne and satellite measurements, depicts variations in Earth's gravity field. As Astronomy Picture of the Day explained when they ran a similar image in 2014: "High areas on this map, colored red, indicate areas where gravity is slightly stronger than usual, while in blue areas gravity is slightly weaker. Many bumps and valleys can be attributed to surface features, such as the North Mid-Atlantic Ridge and the Himalayan Mountains, but others cannot, and so might relate to unusually high or low sub-surface densities." In addition, processes happening deep in the Earth's mantle—such as descending tectonic plates and hot mantle plumes—can also affect the strength of the gravitational field
