Unformatted text preview:  The eccentricity is a measure of the elongation of an ellipse. It is defined as: \begin{equation} \epsilon = \sqrt{1  \frac{b^2}{a^2}} \end{equation} where $a$ and $b$ are the semimajor and semiminor axis lengths respectively. Aphelion  The point of a planet's furthest distance from the sun on its orbit. Perihelion  Is the point of a planet's closest approach to the sun. Apogee  For an earth orbit, the furthest distance from the earth. Perigee  For an earth orbit, the closest distance to the earth....
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 Fall '10
 DavidJudd
 Physics, Celestial mechanics, Earth orbit

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