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# Section 1 : Earth in Space

## #1    How does earth move in space?

Earth moves through space in two ways: rotation and revolution.

Revolution is the movement of one object around another. One complete revolution of Earth around the sun is called a year.

Rotation is the spinning of earth on its axis. Earth's rotation caused day and night.

## #2    What causes the cycle of seasons on Earth?

Earth has seasons it's axis is tilted as it revolves around the sun.

If Earth's axis weren't strait up and down relative to it's orbit, temperatures would remain fairly constant year-round. There would be no seasons if it wasn't this way.

# Section 2: Gravity and Motion

## #1    What determines the strength of the force of gravity between two objects?

The strength of the force of gravity between two objects depends on two factors: the masses of the objects and the distance between them.

## #2     What two factors combine to keep the moon and earth in orbit?

Inertia and gravity combine to keep Earth in orbit around the sun and the moon in orbit around earth.

# Section 3: Phases, Eclipses, and Tides

## #1    What causes the phases of the moon?

The changing relative positions of the moon, earth, and sun cause the phases of the moon, eclipse, and tides. The phase of the moon you see depends on how much of the sunlit side of the moon faces Earth.

## #2    What are solar and lunar eclipses?

When the moons shadow hits Earth or Earth's shadow hits the moon, and eclipse occurs.

A solar eclipse occurs when the moon passes directly between the Earth and the sun, blocking sunlight from Earth.

A lunar eclipse occurs when Earth blocks sunlight from reaching the moon.

## #3    What causes the tides?

Tides are caused mainly by differences  in how much the moon's gravity pulls on different parts of Earth.

# Section 4: Earth's Moon

## #1      What features are found on the moon's surface?

The features on the moon's surface include maria, craters, and highlands.

## #2     What are some characteristics of the moon?

The moon is dry and airless. Compared to Earth, the moon is small and has large variations in its surface temperature.

## #3    How did the moon form?

Scientists theorize that a plane-sized object collided with Earth to form the moon but, we don't know this for a fact. We don't know the truth so they put this as their best guess.