1. May the Force Be With You
Gravity
May the Force Be With You

2. What is Gravity?
Every object in the universe has a mass that exerts a pull (force) on every other mass.
The force of gravity depends on the mass of the object and the distance between objects.

3. What is Gravity?
Example: You don’t get pulled from your seat into the Sun because the Sun is too far away for its gravitational force to be strong.

4. Law of Universal Gravitation
Newton’s law of universal gravitation, states that the gravitational force between two objects is proportional to the mass of each and inversely proportional to the distance between them.

5. Law of Universal Gravitation Illustrated
Large Mass
Small Mass
Far Apart
Weaker Attraction
Large Mass
Larger Mass
Close
Stronger Attraction

6. Effects of Sun & Moon
A gravitational attraction between the Earth and Sun can increase the effect of the Moon on tides.

7. Planets & Moons
Planets are larger than their moons and keep the moons from falling away from the planet.
The moons would travel in a straight line without a force acting on it.

8. Earth and Objects in Space
Because of the Earth’s gravity, satellites and the International Space Station (ISS) orbit the Earth.
Astronauts appear to be weightless because the Earth’s gravity is constantly pulling the vehicle out from under their feet. The vehicle has a much larger mass than their bodies.

9. Sun & Solar System Objects
The solar system is shaped much like an old record; most objects of the solar system stay within the area of a large circular slice of space.

10. Sun & Solar System Objects
The Sun and most of the planets and their moons (except for the dwarf planet Pluto and the comets) keep within this relatively narrow band of space.

11. Sun & Solar System Objects
As the planets travel along the ecliptic, they can occasionally form a straight line across the sky which would rarely happen if they were traveling randomly across the entire sky.
A popular myth is that some terrible disaster will occur when this alignment occurs.

12. Planetary Alignment
On May 5, 2000, the planets Mercury, Venus, Earth, Mars, Jupiter, and Saturn were positioned in a line with the Sun. Also, the Moon was almost lined up between the Earth and Sun.
There were many predictions of global catastrophes such as melting ice caps, earthquakes, etc.
Nothing happened.

13. Planetary Alignment
The distance to the planets is too great for their gravity, magnetic fields, radiation, etc. to have any noticeable effect on Earth.
The inner six planets align every fifty to a hundred years or so.

14. Planetary Alignment
While unusual, such alignments have happened in the past without any consequences.
The planets are simply too far away to have an affect on anything here on Earth.

15. Reflection Questions What is gravity? How does gravity affect objects?
How do the objects in our solar system stay in their respective orbits?