Conceptual Physics

(Sean Pound) #1

(Both terms come from the Greek, “far from the Sun” and “near the Sun” respectively.)


Halley’s comet has an eccentricity of 0.97. We show the comet’s orbit in Example 1, but
for visual clarity it is not drawn to scale. The comet’s orbit is so eccentric that its
maximum distance from the Sun is 70 times greater than its minimum distance. In
Example 1, you calculate the perihelion of this object in AU. The AU (astronomical unit)
is a unit of measurement used in planetary astronomy. It is equal to the average radius
of the Earth’s orbit around the Sun: about 1.50×10^11 meters.


Semimajor axis


a = semimajor axis


rmin = minimum orbital distance


rmax = maximum orbital distance


Eccentricity


e = eccentricity


d = distance from center to focus


a = semimajor axis


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