**The True Shape of Earth**

The true shape of the Earth can be described as an oblate spheroid, which means it is mostly spherical but slightly flattened at the poles and bulging at the equator. This shape is also referred to as a geoid, which represents the Earth's gravitational field.

**Evidence Supporting the Shape**

There are several lines of evidence that support the understanding of the Earth's true shape:

1. **Satellite Images**: Satellite images of the Earth taken from space clearly show a round shape with a noticeable bulge at the equator. These images provide visual evidence of the Earth's oblate spheroidal shape.

2. **Gravity and Earth's Mass**: The Earth's gravitational force is uniform and attracts objects towards its center. This force is stronger at the poles due to the Earth's mass being concentrated closer to the center. The equator, on the other hand, experiences a weaker gravitational force due to the centrifugal force caused by the Earth's rotation. This distribution of gravity is consistent with the oblate spheroidal shape.

3. **Geodetic Surveys**: Geodetic surveys involve the measurement of the Earth's surface using sophisticated instruments and techniques. These surveys have revealed that the Earth is not a perfect sphere, but rather an oblate spheroid. The measurements show a difference in the Earth's radius between the equator and the poles, supporting the concept of the Earth's bulging at the equator.

4. **Gravitational Field Modeling**: Scientists have developed complex mathematical models to represent the Earth's gravitational field. These models take into account various factors such as the Earth's rotation, mass distribution, and gravitational interactions with other celestial bodies. These models consistently predict an oblate spheroidal shape, which is in agreement with observations.

**Conclusion**

In conclusion, the true shape of the Earth is an oblate spheroid or geoid, meaning it is mostly spherical but flattened at the poles and bulging at the equator. This understanding is supported by satellite images, gravitational measurements, geodetic surveys, and mathematical modeling. The Earth's shape has been scientifically established and continues to be a fundamental concept in various fields of study such as geodesy, geophysics, and astronomy.

Since the Earth is flattened at the poles and bulges at the equator, geodesy represents the shape of the Earth with an oblate spheroid. The oblate spheroid, or oblate ellipsoid, is an ellipsoid of revolution obtained by rotating an ellipse about its shorter axis.