In astronomy, Kepler's laws of planetary motion are three scientific laws describing the motion of planets around the Sun.
1. The orbit of a planet is an ellipse with the Sun at one of the two foci.
2. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.
3. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.
Most planetary orbits are almost circles, and careful observation and calculation is required
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