Movements of the Earth: Gravity, Inertia, Rotation, Revolution

Gravity Gravity 1. Pulling force that attracts objects 2. Pulls things down on Earth

Gravity Less Gravity More Gravity 3. Every object has gravity Gravity 4. Strength depends on mass & distance between objects Gravity Less Gravity More Gravity

Gravity Gravity Less gravitational pull More gravitational pull

A space station is to be located between the Earth and the Moon at the place where the Earth’s gravitational pull is equal to the Moon’s gravitational pull. Which of these locations would be best? Explain a b c

Gravity What does gravity do? 1. Holds planets in paths around sun

Gravity What does gravity do? 2. Keeps moon in its orbit around the Earth

Gravity What does gravity do? 3. Keeps entire universe moving in an orderly way

Inertia Inertia 1. Every object in universe is moving

Inertia Inertia 2. A body in motion stays in motion 3. A body at rest stays at rest 4. Unless acted on by a force

Inertia Inertia 5. Every object tries to stay the way it is Either moving or resting

Inertia 1. Moon to keep moving around Earth 2. Planets to keep orbiting the sun What does inertia cause in space?

Inertia What does inertia cause in space? 3. Galaxies to keep moving through space

EARTH Parts of the Earth 1. Equator- horizontal line dividing north and south hemispheres

EARTH Parts of the Earth 2. Latitude- horizontal lines 3. Longitude- vertical lines

EARTH Parts of the Earth 4. Hemispheres- N & S, E & W

EARTH Parts of the Earth 5. Earth’s axis is tilted 23.5 degrees

EARTH’S MOVEMENTS Earth’s movements 1. Rotation- spins like a top 2. Revolution- moves around sun (30km/sec) in oval path

EARTH’S MOVEMENTS ROTATION 1. Earth spins on its axis 2. 24 hours= one rotation 3. Causes night and day 4. Side of Earth facing sun has day

EARTH’S MOVEMENTS REVOLUTION 1. Earth goes around sun (orbits) 2. Takes 1 year = 365 1/4 days 3. Causes seasons 4. Hemisphere tilted toward sun has summer

EARTH’S REVOLUTION SEASONS 2. When north hemisphere is tilted toward sun = summer More direct, intense light rays, warm Earth more

EARTH’S REVOLUTION SEASONS 3. When north hemisphere is tilted away sun = winter Weaker, spread out light rays, warm Earth less

EARTH’S REVOLUTION SEASONS 4. When n. hemi has winter, s. hemi has summer

EARTH’S REVOLUTION SEASONS 5. Spring and Fall occur when neither hemisphere is tilted toward or away from the sun Equinoxes

Diagram of Earth’s Seasons