#38 The Earth-Moon System

Approximately how many billion years ago did the Moon form?

• 3.5 billion years

• 4.5 billion years

• 5.5 billion years

• 6.5 billion years

What is the phenomenon called when the same side of the Moon always faces the Earth?

• Solar locking

• Tidal locking

• Lunar locking

• Gravitational locking

What is the angle of the Moon's orbit compared to the Earth's tilt?

• 15°

• 23.4°

• 5°

• 10°

What is the term for the common center around which the Earth and Moon orbit?

• Axis

• Barycenter

• Equator

• Meridian

How long does it take for the Moon to complete one orbit around the Earth?

• 30 days

• 27.3 days

• 29 days

• 31 days

What evidence supports the hypothesis that the Moon formed from debris after a collision?

• The Moon has a higher density than Earth

• The Moon has a lower density than Earth

• The Moon has the same density as Earth

• The Moon has a variable density

What is the Moon's role in the Earth-Moon system?

• It is a planet

• It is a natural satellite

• It is a star

• It is an asteroid

What is the effect of the Earth's gravity on the Moon's rotation?

• Speeds it up

• Slows it down

• Stops it

• Reverses it

What is the significance of the Moon's isotope ratios?

• They suggest the Moon is older than Earth

• They suggest the Moon formed at the same time as Earth

• They suggest the Moon is younger than Earth

• They suggest the Moon formed from a different solar system