The diameter of Earth is 7,917.5 miles. The diameter describes a straight line that passes from one side of the planet to the next, going through the center of Earth.
Exploring the Earth’s Radius
At the equator, the radius of Earth is approximately 3,963 miles. What is interesting is that this planet is not a perfect sphere. At the equator, there is a bulge that occurs as a result of the planet’s rotation. There is a difference of approximately 14 miles at the polar radius of the Earth compared to the equator. This distance is 3,949 miles.
Since Earth is not considered to be a perfect sphere, there is a special name for it. This is called an oblate spheroid. This refers to a sphere where at the poles, some flattening occurs.
Polar vs. Equatorial Diameter
Compared to objects at the poles, those at the equator are about 21 kilometers further away from the Earth’s center. When you explore local topography, there are some natural deviations associated with this. For example, there can be differences in the distance of two objects within the same region due to topography deviations. One of the biggest exceptions to this are Mt. Everest and the Mariana Trench. When compared to the overall shape of the planet, these two elements have a minor variation that scientists have documented.
While there are certainly larger planets, Earth has a rather impressive diameter. You can see that other measurements associated with the planet are also quite large. Learning more about the sheer size of the planet gives you a better idea about where you live. Think about your city and its diameter and compare this to the Earth’s total diameter. This gives you an idea of how small many places within the planet actually are.