Earth is approximately spherical, not flat.
Measurements from the ground and space agree: Earth is a slightly flattened sphere, with an uneven surface.
Show me why
Earth is round at planetary scale. Its rotation produces a small equatorial bulge, and mountains and ocean trenches make its surface irregular. Geodesists use an ellipsoid for a practical approximation and a geoid to describe a gravity-based reference surface.
A common misconception
A flat-looking horizon at ordinary viewing height does not establish a flat planet.
Where the limits are
“Spherical” is an approximation, not a claim that Earth is a mathematically perfect sphere.
How we know
Compare the NOAA explanation of shape with its account of geodetic measurement. These models must support consistent measurements around the whole planet. A locally level patch of ground is compatible with a large curved surface; a single photograph or a short horizon view is not a complete shape measurement.
What would change this conclusion?
A reproducible alternative would need to fit global survey, navigation and space observations better than the ellipsoidal model.
Sources you can inspect
- NOAAIs the Earth round?
Explains the ellipsoid approximation and irregular shape.
Updated 2026-09-23 · Checked in initial research 2026-10-08 - NOAAWhat is Geodesy?
Describes how shape and gravity are measured.
Updated 2026-09-23 · Checked in initial research 2026-10-08
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