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Orbital eccentricity

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# Keplerian Elements : Orbital Eccentricity and Semi Major Axis

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What is eccentricity?

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Obliquity, eccentricity, precession: Milankovitch Cycles

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Jesus X - Orbital Eccentricity (Prod. by Rich Mitcheee)

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Teach Astronomy - Orbit Eccentricity

The orbital eccentricity of an astronomical object is a parameter that determines the amount by which its orbit around another body deviates from a perfect circle. A value of 0 is a circular orbit, values between 0 and 1 form an elliptic orbit, 1 is a parabolic escape orbit, and greater than 1 is a hyperbola. The term derives its name from the parameters of conic sections, as every Kepler orbit is a conic section. It is normally used for the isolated two-body problem, but extensions exist for objects following a Klemperer rosette orbit through the galaxy.