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Periapsis


ApoapsisPeriapsis

The smallest radial distance of an ellipse as measured from a focus. Taking v=0 in the equation of an ellipse

 r=(a(1-e^2))/(1+ecosv)

gives the periapsis distance

 r_-=a(1-e).

Periapsis for an orbit around the Earth is called perigee, and periapsis for an orbit around the Sun is called perihelion.


See also

Apoapsis, Eccentricity, Ellipse, Focus

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Cite this as:

Weisstein, Eric W. "Periapsis." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/Periapsis.html

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