2.  Everything in outer space  Stars  Planets  Comets  Asteroids & Meteors  Solar System vs Galaxy vs Universe  What’s the difference?  SIZE?!

3.  Imaginary sphere around the earth that all objects appear to be on.

4.  Everything moves in space.  Why? Because of gravity.  Yes there is gravity everywhere.

5.  Orbits  Movement of planets around a central body that is elliptical  Rotation  Planetary movement on its axis  Revolution  Planets moving around on its orbit

6.  This is the force that pulls on other objects.  What causes it?  Mass of an object causes an attraction between them.  So if you have mass there is gravity.

7.  Gravity has three laws  1 st law ▪ Object at rest will stay at rest until acted upon by another force.  2 nd law ▪ An object will move if the force is greater then the mass.  3 rd law ▪ When an object applies a force on a surface the surface pushes back with equal force.

8.  Earth rotates 15 o per hour

9.  Answer the questions solo and we will review in 10 minutes.  Use your notes to answer the questions.

10.  Geocentric  Earth Centered.  Circular orbits  Ptolemy,  Retrograde motions  Heliocentric  Sun Centered  Circular orbits  Copernicus, Kepler and Galileo  Daily movements

11.  Pendulum  As the earth rotates it allows the pendulum to swing.  Because the pendulum swings and moves that means the Earth rotates.

12.  Newton – Laws of gravity  Ptolemy – Geocentric model  Copernicus – Heliocentric model