1. Topic: Planetary Motion PSSA: 3.4.7.D/S8.D.3.1

2. Objective: TLW differentiate between rotation and revolution. TLW differentiate between rotation and revolution. TLW state and explain Kepler’s 3 Laws of Planetary Motion. TLW state and explain Kepler’s 3 Laws of Planetary Motion. TLW explain Newton’s Law of Universal Gravitation. TLW explain Newton’s Law of Universal Gravitation.

3. MI #1: Planetary Motion Rotation is the spinning of a planetary body on its axis. Rotation is the spinning of a planetary body on its axis. Orbit is the path that one body follows as it travels around another body. Orbit is the path that one body follows as it travels around another body. The time it takes a planetary body to make one orbit is called its period of revolution. The time it takes a planetary body to make one orbit is called its period of revolution.

4. MI #2: Kepler’s Laws of Planetary Motion 1. Planets revolve around the sun in elliptical orbits; this means their distance from the sun is not constant. 2. Planets move faster when they are closer to the sun in their orbit than when they are further away; this means their speed is not constant. 3. Planets that are further away from the sun take longer to orbit the sun than closer planets.

5. MI #3: Gravity and Planetary Motion Newton said that the force of gravity between two objects is due to their masses and the distance between them Newton said that the force of gravity between two objects is due to their masses and the distance between them Because planetary bodies are in motion in addition to being pulled by the sun’s gravity, they do not go flying into the sun. Because planetary bodies are in motion in addition to being pulled by the sun’s gravity, they do not go flying into the sun.

6. So What…? Real Life Application Understanding planetary motion allows scientists to study planets and their moons in more detail and make predictions about eclipses, tides, etc. Understanding planetary motion allows scientists to study planets and their moons in more detail and make predictions about eclipses, tides, etc.