TOPIC 4

How does the Earth rotate?

The Earth spins on its axis which, is an imaginary line through the planet from the north to the south pole.

What is the evidence for Earth’s rotation?

• Foucault Pendulum-(a mass attached to an arm, that swings freely) Its path will appear to change in a predictable way. This is evidence because the pendulum, due to inertia, would continue to swing in the original path if Earth didn’t rotate.

What is the evidence for Earth’s rotation? continued

• Coriolis Effect- particles of moving matter are deflected or curved away from a straight line path. This is evidence because the Earth surface is rotating W to E– In Northern Hemisphere,

bends to the right– In Southern Hemisphere,

bends to the left

What is an effect of Earth’s Rotation?

• Day and Night

• Apparent path of stars and the moon

How does the Earth revolve?

It revolves around the sun in a slightly eccentric elliptical orbit. – Once around the sun=one year

What is the evidence for Earth’s revolution?

A) Parallax- Constellations that are visible all year round appear in slightly different positions because our position changed

What is the evidence for Earth’s revolution? continued

Constellations- A group of stars that form a pattern. Each season has associated constellations with it.

What is the evidence for Earth’s revolution? continued

• Seasons- If the Earth was in the same location in its revolution all year long, there would be no change in seasons. Essentially you would have the same season all year long. They are a cyclic change

What are effects of the Earth’s Revolution?

• Cyclic changes occur in temperature

• Orbital velocity changes

• Apparent diameter of the sun

• Gravity force between Earth and Sun changes