Kepler’s Laws of Planetary Motions 1. Planets move in elliptical orbits with the sun at one of the foci SUN Foci – 2 points that are equidistant from center on major axis

2. Law of Areas Line from the sun to a planet sweeps with equal areas in equal time. A planet will move through equal area of space in an equal amount of time Perihelion – closest to sun Ahelion – farthest from sun i. When a planet is in perihelion its orbital velocity increases ii. When a planet is in aphelion its orbital velocity decreases

Farthest from sun Slower Velocity Closer to the sun, faster the velocity because of the gravitational pull. Closest to sun Faster Velocity Greater Gravitational Pull

3. Law of Periods - The farther a planet is from the focus, the longer the period of revolution. Ex: Earth is closer to the sun than Jupiter, therefore the Earth has a shorter period of revolution. (ESRT)

• Newton’s Law of Gravity • • • The force of attraction between any two objects depends on their masses and the distance between them. Thus, the closer the objects, the greater _______ the gravitational pull Thus, the bigger the object the _____ greater the gravitational pull

Closer to the sun in the winter, farther from sun in summer