The pull of gravity doesn't *directly* indicate that Earth is a sphere. It's more accurate to say that the distribution of gravity on Earth's surface is consistent with a *spherical shape*. Here's how:

* Gravity is strongest at the poles and weakest at the equator: This is because the Earth is slightly squashed at the poles and bulges at the equator (an oblate spheroid). This means you're closer to the center of mass at the poles than at the equator.

* Gravity pulls towards the center of mass: For a spherical object, this means gravity pulls directly down towards the center at any point on the surface.

* Observations of gravity: We can measure gravity very precisely using instruments called gravimeters. These measurements show a consistent pattern of increasing gravity towards the poles and decreasing gravity towards the equator. This pattern can be explained by the Earth's oblate spheroid shape.

* Satellite data: Satellites orbiting Earth experience variations in gravity due to Earth's shape. This data further supports the idea of an oblate spheroid.

In summary:

While the pull of gravity itself doesn't directly reveal Earth's shape, the way gravity varies across the planet's surface is consistent with the shape of an oblate spheroid. This consistency is what allows us to conclude that Earth is not a perfect sphere, but rather a slightly flattened sphere.