Gravitation – Notes
Kepler’s Law of Gravitation
To resolve shortcomings of the models propounded by Ptolemy and Copernicus, Kepler propounded three laws on planetary motion.
Kepler’s first law, the law of orbits, states that the orbit of a planet is an ellipse with the sun at one of the foci.
An ellipse is a closed, curved shape that is defined by two points called foci representing an elongated circle.
The perihelion is the closest point on a planet’s orbit from the sun.
The aphelion is the farthest point on a planet’s orbit from the sun.