A spheroid is a surface of revolution formed by rotating an ellipse about one of its axes. Equivalently an ellipsoid is a spheroid if two of its axes are of equal length. The spheroid is oblate if the axis of rotation is the minor axis and prolate if the axis of rotation is the major axis. The Earth is approximately an oblate spheroid.
Oblate spheroid with vertical axis
Prolate spheroid with vertical axis
A body or surface produced by rotating an ellipse about either its major axis (a prolate spheroid) or its minor axis (an oblate spheroid). Both are special cases of an ellipsoid. The Earth’s shape is very nearly that of an oblate spheroid, its equatorial radius being 21 km greater than the polar radius, while the equator departs from a circle by less than 1 km.
The surface produced when an ellipse is rotated about one of its principal axes.
- Faraday–Neumann law
- Faraday’s laws
- Faraday’s laws of electrolysis
- Faraday’s laws of electromagnetic induction
- farad(symbol: F)
- Farallon Plate
- far encounter phase
- far-end crosstalk
- far-field barrier
- far-field region
- far infrared
- farm
- Farm Credit System
- farmers-general
- farm fragmentation
- farming
- farm subsidies
- Farnese
- Farouk (1920–65)
- far out
- farra
- Farrakhan, Louis
- farrum
- Farr, William (1807–83)
- far ultraviolet