Ch 20 Sun Earth Moon

the star at the center of the Solar System that supplies heat and light to earth; its enormous gravity keep the Solar System in orbit.

• satellite
• sun
• craters
• moon

a natural force that causes two objects to pull toward each other on their mass and the distance between them.

• gravity
• orbit
• atmosphere
• axis

the path one object takes as it revolves (moves) around another object.

• gravity
• orbit
• rotate
• axis

a natural satellite that orbits a planet. 

• sun
• atmosphere
• moon
• craters

to spin on an axis

• orbit
• rotate
• axis
• atmosphere

a line, real or imaginary, around which something spins

• orbit
• rotate
• gravity
• axis

As the Moon's phase changes from first quarter to last quarter, the visible portion of the Moon as observed from Earth will

• decrease, only
• increase, only
• decrease, then increase
• increase, then decrease

The time required for the Moon to complete one cycle of phases is about one

• day
• week
• month
• year

The same side of the Moon always faces Earth because the

• Moon's period of rotation is longer than its period of revolution around the Earth
• Moon's period of rotation is shorter than its period of revolution around Earth
• Moon rotates once as it completes one revolution around Earth
• Moon does not rotate as it completes one revolution around Earth

The length of an Earth day is determined by the time required for approximately one

• Earth rotation
• Earth revolution
• Sun rotation
• Sun revolution