1. Kepler’s Three Laws of Planetary Motion

3. 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

4. 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
When a planet is in perihelion its orbital velocity increases
When a planet is in aphelion its orbital velocity decreases

5. Closest to sun Slower Velocity Faster Velocity Farthest from sun
Closer to the sun, faster the velocity because of the gravitational pull.
If the areas of A, B, and C are equal and the time’s for A, B, and C are equal, that means the speed must change in different areas of orbit
Farthest from sun
Closest to sun
Slower Velocity
Faster Velocity
Greater Gravitational Pull

6. 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)

8. 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 ______________ the gravitational pull
Thus, the bigger the object the __________ the gravitational pull
greater
greater

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