What is the furthest distance around the earth?

The Longest Walk: Unraveling Earth’s Furthest Distance

We often think of the Earth as a perfect globe, a sphere of uniform curvature. But the reality is more nuanced. Our planet bulges slightly at the equator and is flattened at the poles, resulting in what’s known as an oblate spheroid. This subtle distortion has a significant impact when we consider the question: what is the furthest possible distance you could travel between two points on Earth’s surface?

Intuitively, one might assume the greatest distance would be half the circumference of the Earth at the equator. After all, the equator is the widest part of the planet. However, due to the polar flattening, the picture changes.

The key lies in understanding that the Earth’s circumference isn’t constant. It varies depending on whether you’re measuring around the equator or through the poles. Because the polar diameter is shorter than the equatorial diameter, a journey spanning the longest possible distance would actually follow a path along a line of longitude, passing over both poles.

Imagine drawing a line from the North Pole to the South Pole, and then continuing along the same longitudinal line on the opposite side of the Earth back to the North Pole. That path, tracing a meridian, represents the maximum separation achievable between two points on our planet.

So, what’s the actual distance? The furthest possible separation between two points on Earth, taking into account its oblate shape and following a line of longitude, is approximately 12,430 miles, which translates to roughly 20,004 kilometers.

This value represents half the polar circumference of the Earth. It’s a fascinating example of how even small deviations from a perfect spherical shape can influence fundamental measurements and how we perceive the distances on our own planet. It also underscores the importance of considering the Earth’s true form when engaging in large-scale mapping, navigation, and other geoscience applications.