Why Earth Is Neither “Square” nor Simply “Round”

By Lena Élyse Kovač

Anyone claiming that Earth might be “square” is setting themselves against the most stubborn reality of all: numbers. But even saying that Earth is “round,” when taken literally, is an imprecise way of describing a physical body that can now be measured with extraordinary accuracy.

1. Not a Ball, but a Flattened Ellipsoid

As a first approximation, Earth is an oblate spheroid—an ellipsoid of revolution—not a perfect sphere.

Equatorial radius: approximately 6,378 kilometres.
Polar radius: approximately 6,357 kilometres.

The difference is therefore about 21 kilometres. That is small enough for the planet to appear spherical to the naked eye, but enormous on geodetic and dynamic scales.

This flattening is a direct consequence of Earth’s rotation. Centrifugal acceleration is greatest at the equator and effectively zero at the poles, altering the distribution of mass relative to that of an ideal sphere.

As a second approximation, the real Earth is described as a geoid: an equipotential surface of the gravitational field that reflects irregularities in the distribution of mass both inside the planet and across its surface. Relative to the reference ellipsoid, the geoid rises or falls by several dozen metres, depending on the region.

2. Why a “Square” Earth Would Not Survive a Single Day of GPS

Imagining a “square” or cubic Earth is not merely wrong in the abstract. It is incompatible with infrastructure that we use every minute.

Satellite navigation systems such as GPS and Galileo depend on:

Satellites orbiting at altitudes of approximately 20,000 kilometres.
Extremely precise measurements of radio-signal travel times, where errors of only a few billionths of a second can translate into positional errors of several metres.
Detailed models of Earth’s gravitational field and satellite positions, incorporating the planet’s ellipsoidal shape and the irregularities of the geoid.

If Earth had flat faces and sharp edges, its gravitational field and satellite orbits would exhibit major discontinuities. Satellite trajectories would diverge from their calculated paths, positioning would suffer systematic errors, and navigation systems could not maintain their present accuracy of a few metres—or even a few centimetres or decimetres when differential corrections are used.

A genuinely “square” Earth would, in practical terms, mean abandoning the internal consistency of everything we now take for granted: accurate intercontinental flights, optimised shipping routes, reliable digital maps, and global logistics.

3. Geodetic Data: A Corrugated Planet, Not a Disc

Modern geodesy, using ground-station networks, radar satellites, and dedicated gravimetric missions, has produced extremely detailed models of Earth’s shape and gravitational field.

Two facts are particularly revealing:

The geoid differs from the reference ellipsoid by several dozen metres. In some regions, this equipotential surface is higher or lower because of variations in the density of the underlying masses, including mountain ranges, deep ocean basins, and anomalies within the mantle.
Real topography—mountains, depressions, and ocean trenches—adds further variations of several kilometres relative to the geoid. Mount Everest rises more than 8,800 metres above sea level, while the Mariana Trench descends to approximately 11,000 metres below it.

We are therefore very far from both a flat disc and a smooth ball. Earth is an object with continuous curvature, whose roughness and elevation differences extend for kilometres vertically and hundreds of kilometres horizontally.

4. Rotation and Orbit: Numbers That Require Curvature

Earth rotates on its axis in approximately 23 hours and 56 minutes—the sidereal day—and completes one orbit around the Sun in approximately 365 days. These figures are not merely features of a calendar. They have measurable consequences for the planet’s shape and for the physical phenomena we observe.

At the equator, Earth’s rotational speed is approximately 1,670 kilometres per hour. The resulting centrifugal acceleration slightly reduces apparent weight compared with the poles. Gravitational acceleration varies from approximately 9.83 metres per second squared at high latitudes to around 9.78 metres per second squared at the equator.
Tiny variations in the length of the day, measured in milliseconds, are connected to redistributions of mass involving water, ice, and the atmosphere, as well as events such as major earthquakes. Measuring and explaining these changes requires a continuous and accurate model of Earth as a rotating, deformable body—not as a rigid solid with flat faces.

All these measurements are compatible with a nearly spherical, slightly flattened, and irregular planet. They are not compatible with a “cosmic square.”

5. The Limits of “Round”: When Simplicity Misleads Us

In everyday language, we say that “Earth is round” to contrast it with the naive idea of a flat Earth. From a physical perspective, however, that statement is now too simplistic.

A perfect sphere is defined by a single radius.

Earth, by contrast, requires:

Different equatorial and polar radii, separated by approximately 21 kilometres.
A description based on a gravitational field that varies from one point to another.
Models incorporating the planet’s elasticity, solid-Earth tides, polar motion, and deformations associated with ice, oceans, and the atmosphere.

Continuing to use “round” as though it were a complete scientific description risks encouraging a distorted perception. On the one hand, it gives conspiracy theorists an easy target: “It is not round in the way you claim, so you must be lying.” On the other, it prevents the public from appreciating how precise and numerically constrained our knowledge of Earth has become.

6. Calling Earth by Its Proper Name

Saying that Earth is not square is almost trivial. Saying that it is not even strictly “round” is an act of honesty toward the evidence.

Earth’s shape is that of an irregular oblate ellipsoid, approximated by a geoid that accounts for the gravitational field, with a surface corrugated by kilometres of elevation differences.

This description may be less elegant, but it has one decisive advantage: it works. It is the model that supports the satellites above our heads, the maps on our phones, and the flights that carry us from one continent to another.

Accepting this complexity is not a defeat for common sense. It is a small victory for intellectual maturity: we stop demanding that the world resemble the geometric figures in our schoolbooks and accept that those figures—and the numbers that define them—must instead adapt to the world.

Lena Élyse Kovač