Abstract:
In 1609 ad, Johannes Kepler proposed a new model for planetary
motion:
- Each Planet follows an elliptical orbit for which the Sun occupies one
focus.
- The line joining the Sun and the Planet sweeps out equal areas in equal
times.
In consequence, the new model required for the location of the Planet
upon its orbit as a function of time, the solution of a transcendental
equation: The Equation of Kepler. Most astronomers, notably Kepler
and Nicholas Mercator, believed the solution to be non-constructible
and they acknowledged the circumstance with regret. Enter Seth Ward
(1656 ad), who proposed an elegant constructive scheme for locating
the Planet upon its orbit as a function of time, by exploiting the
unoccupied focus of the ellipse. He restored, so he said, geometry to
astronomy. The object of this lecture is to set the foregoing issues
in historical context and to describe and evaluate Ward's scheme.
Prerequisite: Trigonometry.
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