Kepler's Laws of Planetary Motion: Kepler's First Law (1609): The orbit of a planet about a star is an ellipse with the star at one focus. Kepler's Second Law (1609): A line joining a planet and its star sweeps out equal areas during equal intervals of time. Kepler's Third Law (1618): The square of the sidereal period of an orbiting planet is directly proportional to the cube of the orbit's semimajor axis. Kepler's first law(the law of …showed first 75 words of 337 total…

…showed last 75 words of 337 total…resembles the shape of a circle. In fact, a circle is the special case of an ellipse in which the two foci are at the same location. Kepler's Second Law(the law of equal areas): It describes the speed of any planet movement while it is in the suns orbit. The speed constantly changes. A planet moves fastest when it is close to the sun and moves slow when it is further from the sun.