1. How does the geocentric model differ from the heliocentric model?
DO NOW
How does the geocentric model differ from the heliocentric model?
AIM
How did early astronomers prove the Earth rotates and how is time determined?

2. How did astronomers prove the Earth rotates?
Leon Foucault (1851)
Foucaults pendulum- a free swinging pendulum that appears (apparent motion) to change position because of the Earth’s rotation.

3. Coriolis Effect- the apparent curve of a moving object caused by the Earth’s rotation.

5. How did early astronomers prove the Earth revolves around the sun?
The change in the seasons.
Observing different constellations at different times of the year.

6. The apparent diameter of the sun changes throughout the year (larger during perihelion and smaller during aphelion).

7. The History of Time
The actual motions of the Earth and/or the moon as a frame of reference is used to determine time.
1 year = 1 revolution around the sun and is measured by the changes in apparent motions of the sun and stars.
1 month = 1 cycle of our moon’s phases.
1 day = 1 rotation of the Earth on its axis.

8. What is local time?
Local Time- time based on the rotation of the Earth as reflected in motions of the sun a.k.a SOLAR TIME.
Sundial- records local time by the shadow casted by the sun.

9. How are time zones established?
Time zones were created to standardize time for regions.
The Earth rotates 360° in 24 hours. 360°/24 = 15°.
24 separate time zones each 15° of longitude apart, each 1 hour difference in time.