Tuesday, October 16, 2012

Eccentricity - Definition

Eccentricity

Eccentricity is a measure of how an orbit deviates from circular. A perfectly circular orbit has an eccentricity of zero; higher numbers indicate more elliptical orbits.


Neptune, Venus, and Earth are the planets in our solar system with the least eccentric orbits. Pluto and Mercury are the planets in our solar system with the most eccentric orbits.



A value that defines the shape of an ellipse or planetary orbit. The eccentricity of an ellipse (planetary orbit) is the ratio of the distance between the foci and the major axis. Equivalently the eccentricity is (ra-rp)/(ra+rp) where ra is the apoapsis distance and rp is the periapsis distance.

Source: wikipedia, NASA

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