The point on Earth closest to space is not Mount Everest

3 min read

Ask which mountain is the highest on Earth and almost everyone will say Mount Everest. Measured as height above sea level, that answer is correct. But there is another way to ask the question: which point on the ground is farthest from the centre of the planet, and so closest to space? By that measure, the winner is a snow-capped volcano in Ecuador called Chimborazo.

A planet with a waistline

Earth is not a perfect sphere. As it spins, the rotation pushes material outward at the Equator, so the planet is slightly wider around the middle than it is from pole to pole. Geodesists call this shape an oblate spheroid. The difference is small compared with the size of the planet, but it adds up to roughly 21 kilometres between the equatorial and polar radius. Anyone standing near the Equator is therefore already a little farther from Earth’s centre than someone standing near the poles.

Why Chimborazo comes out on top

Chimborazo rises to 6,268 metres above sea level, more than two and a half kilometres lower than Everest. The difference is where the two mountains stand. Everest lies in the Himalayas at about 28 degrees north, while Chimborazo sits roughly one degree south of the Equator, right on top of the widest part of the bulge. That head start more than makes up for its lower elevation.

According to the US National Oceanic and Atmospheric Administration, the result is that Chimborazo’s summit is more than 2,072 metres farther from the centre of the Earth than Everest’s peak. Standing on top of it, you are as close to the stars as it is possible to be while still standing on solid ground.

Three ways to be the biggest

The comparison shows that “tallest” depends on what you measure. Everest has the highest summit above sea level. Chimborazo has the summit farthest from Earth’s centre. And if you measure a mountain from its base to its peak, the record goes to Mauna Kea in Hawaii, a volcano that begins deep on the floor of the Pacific Ocean and rises more than 10,210 metres in total, although much of that height is hidden underwater.

Measuring a moving target

Working out these figures takes careful surveying. Agencies such as NOAA’s National Geodetic Survey model the precise shape of the planet, its gravity and the level of the sea so that heights around the world can be compared fairly. Their work is what reveals that a mountain few people outside South America know by name holds a record that Everest cannot claim.