A spheroid, also known as an ellipsoid of revolution or rotational ellipsoid, is a three-dimensional shape obtained by rotating an ellipse about one of its principal axes. It is a surface of revolution and can have two equal semi-diameters, making it an ellipsoid with circular symmetry. The longer radius of the ellipse is called the semimajor axis, and the shorter radius is called the semiminor axis. Rotating the ellipse around the semiminor axis creates an oblate spheroid, while rotating it around the semimajor axis creates a prolate spheroid.
Spheroids have various applications and meanings in different fields:
- In geodesy, a spheroid is used to represent the shape of the Earth. The current World Geodetic System model uses a spheroid with specific radii at the Equator and the poles
- In mathematics, a spheroid is an ellipsoid with two axes of equal length
- In cell biology, spheroids are three-dimensional cell aggregates that can mimic tissues and microtumors. They are used as models for in vivo tissue environments
- In general usage, a spheroid refers to any object that resembles a sphere or has an approximately spherical shape.
Overall, a spheroid is a geometric shape that is formed by rotating an ellipse, and it has various applications and meanings in different fields.
