1. The
orbits of the planets are elliptical, with the Sun
at one focus.
2. An imaginary
line joining a planet
to the Sun sweeps out equal areas in equal times.
(Click and drag blue bar to resize orbit. Click in the black area to toggle equal-area law illustration.)
3. The square of a planet's period is proportional to the cube of its semi-major axis.
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Copyright © 1997 M. S. Pettersen
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This page was last updated November 18, 1997.