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Kepler’s laws of orbital motion show the effects of gravity on orbits. Kepler’s first law describes the shape of an orbit. Kepler’s second law describes the way an object’s speed varies along its orbit.  And Kepler’s third law compares the motion of objects in orbits of different sizes. Kepler’s three laws are universal and apply to any object that orbits another: Earth orbiting around the Sun, moons orbiting around planets, spacecraft orbiting around Earth.