Kepler's 1st law: law of ellipses Stationary objects resist movement, and moving objects resist stopping. 2. Kepler's 2nd law: law of equal areas The greater the mass, the stronger the gravitational force. The greater the distance, the weaker the gravitational force. 3. Kepler's 3rd law: harmonic law Acceleration of an object depends on its mass and applied force. 4. Newton's 1st law of motion An imaginary line joining a planet to the Sun sweeps out equal areas in equal amounts of time. 5. Newton's 2nd law of motion Planets closer to the Sun orbit it in a shorter time period than planets further from the Sun. 6. Newton's 3rd law of motion The orbit of planets is not circular but elliptical. 7. Newton's law of universal gravitation For every action, there is an equal and opposite reaction.