Planets travel in orbits that are elliptical. Kepler's 1st law of motion relates the shape of a planet's orbit with its speed. This law states that:
All planets move in an orbit, with the sun at one of the two foci.
Additionally, Kepler's other laws are as follows:
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Kepler's 2nd law states that: As a planet orbits the sun, an imaginary line from the center of the planet to the center of the sun sweeps out equal intervals of time.
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Kepler's 3rd law states that: The square of the period of any planet about the sun is proportional to the cube of the planet's mean distance from the sun.