oblate spheroid

geometry

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Last updated

July 1, 2026

Quick Summary

An oblate spheroid is a type of ellipsoid formed by revolving an ellipse about its minor axis. This shape is characterized by having two equal semiaxes and one different semiaxes, where the two equal axes are longer than the third.1

A key example of an oblate spheroid is the shape of the Earth, which bulges at the equator due to its rotation. This geometric shape is distinct from a prolate spheroid, which is generated by revolving an ellipse about its major axis.12

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ellipsoid
…than c, the spheroid is oblate; if less, the surface is a prolate spheroid.
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…than c, the spheroid is oblate; if less, the surface is a prolate spheroid.
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geoid
Ellipsoidal era
…conceive of Earth as an oblate spheroid. In one of the many brilliant analyses in his Principia, published in 1687, Newton deduced Earth’s shape theoretically and found that the equatorial semiaxis would be 1/230 longer than the polar semiaxis (true value about 1/300).
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…conceive of Earth as an oblate spheroid. In one of the many brilliant analyses in his Principia, published in 1687, Newton deduced Earth’s shape theoretically and found that the equatorial semiaxis would be 1/230 longer than the polar semiaxis (true value about 1/300).
Read More