Question 1

What will most likely be the fate of the footprints that the astronauts left on the Moon?

Accepted Answer

The Moon is constantly bombarded by micrometeorites and other particles, which will gradually erode and erasure the footprints left by the astronauts over time. While there is no atmosphere on the Moon to cause wind erosion, these small impacts will eventually fill in the depressions left by the footprints.

Question 2

In what fundamental way do lunar rocks differ from terrestrial rocks?

Accepted Answer

Lunar rocks contain no water within their crystal structure, whereas terrestrial rocks can contain water in their crystal structure.

Question 3

Suppose that two regions on the Moon have ages, respectively, of 3.7 and 4.3 billion years. Based on these ages, we expect to find that:

Accepted Answer

The older region has had more time to accumulate impacts, leading to a higher number of craters compared to the younger region. The cratering rate in the solar system has varied over time, but generally, older surfaces are more heavily cratered due to the longer exposure to potential impactors.

Question 4

After the initial formation of the solar system, rocky debris:

Accepted Answer

The period of time during which rocky debris continued to bombard the planets and satellites after the initial formation of the solar system is known as the Late Heavy Bombardment. This period lasted for almost another billion years after the solar system's formation. Therefore option C is the best choice. Options A, B, and D are incorrect as they do not align with our current understanding of the early solar system.

Question 5

We believe the rate of bombardment of projectiles striking bodies in the inner solar system decreased steadily except for a sharp increase between 3.8 and 4.0 billion years ago. What is believed to be the cause of this increase?

Accepted Answer

The increase in bombardment between 3.8 and 4.0 billion years ago is believed to be caused by the migration of Jupiter and Saturn to their current orbits. This movement disturbed the asteroid belt, sending many objects into the inner solar system.

Question 6

The ages of Moon rocks have been found through radioactive dating. One major difficulty with this technique is that:

Accepted Answer

The original abundances of the elements are not precisely known, which can affect the accuracy of the age determination through radioactive dating.

Question 7

What is a transient lunar phenomenon?

Accepted Answer

A transient lunar phenomenon occurs when a small body with a diameter of around 10cm strikes the Moon's surface and emits enough light to be seen from Earth.

Question 8

If the rate at which the Moon is moving away from Earth remains approximately constant at 4 cm per year, how long will it take for the distance between Earth and the Moon to increase by 10%?

Accepted Answer

The current average distance from the Earth to the Moon is about 384,400 km. A 10% increase in this distance would be approximately 38,440 km. Since the Moon is moving away at a rate of 4 cm per year, it would take about 1 billion years to move 38,440 km (38,440,000 meters / 0.04 meters/year = 961,000,000 years, which rounds to approximately 1 billion years).

Question 9

Which statement best describes the average relationship between passage of the Moon through an observer's meridian and the occurrence of high tide in the open ocean? (Hint: See Figure 10-20 of Universe, 11th ed., and think about what you would experience on Earth.)
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Accepted Answer

The answer of Which statement best describes the average relationship...

Question 10

Earth's rotation is slowing down because of the tidal interaction between Earth and the Moon at a rate of 2 milliseconds per century. If this rate remains constant at the present value, how long will it take for 1 day on Earth to become 2 seconds longer than it is now?

Accepted Answer

If Earth's rotation is slowing down at a rate of 2 milliseconds per century, then it will take 500,000 centuries (1000/2) for 1 day (24 hours) to become 2 seconds longer. 500,000 centuries is equal to 50,000 years, so the answer is D) 100,000 years.

Question 11

Moon rocks contain no water in their crystal structure and contain far less volatile material than those on Earth. Which theory of the origin of the Moon provides the most likely explanation for these differences?

Accepted Answer

The theory of a collision between Earth and a large meteoroid explains that the ejection of hot material into orbit around Earth would have been depleted in volatile materials. This matches the observations of the Moon rocks that contain less volatile material than those on Earth.

Question 12

Compared to rocks on Earth, lunar rocks are:

Accepted Answer

Lunar rocks are slightly depleted in elements that melt at low temperatures because the Moon had a global melting event early in its history that caused these elements to separate from the molten rock and escape to the surface. Lunar rocks are enriched in elements that melt at high temperatures because these elements remained in the molten rock and became concentrated as it cooled and solidified. Lunar rocks contain no water of crystallization because there is no liquid water on the Moon.

Question 13

One theory about the origin of the Moon states it was formed from debris thrown out when a Mars-sized object collided with Earth. One fact that strongly supports this theory is that:

Accepted Answer

The similarity in composition between Moon rocks and Earth rocks, especially the depletion in elements that melt at low temperatures, supports the theory that the Moon was formed from debris resulting from a massive collision with Earth. This is because the heat of such an impact would have melted those elements, causing them to vaporize and be lost from the debris that formed the Moon.

Question 14

What can be said to evaluate the fissure theory of the Moon's origin-the theory that Earth was spinning so rapidly in its semimolten state that a large piece flew out and cooled to become the Moon?

Accepted Answer

The Pacific Ocean Basin is explained by the theory of continental drift as a transient feature, not as evidence of a piece of Earth being torn out, which counters the fissure theory's suggestion that the Moon was formed from such an event.

Question 15

What factor is now thought to have played a major role in such diverse events as the formation of the Moon, the tilting of Earth's spin axis, and even the extinction of the dinosaurs?

Accepted Answer

Collisions between asteroid-like bodies and Earth are now thought to have played a major role in events such as the formation of the Moon, the tilting of Earth's spin axis, and the extinction of the dinosaurs. These events were caused by large asteroids or comets colliding with Earth and causing significant impact damage.

Question 16

The theory that seems to account most satisfactorily for the origin of the Moon at the present time is that:

Accepted Answer

The giant-impact hypothesis, which suggests that the Moon formed from the debris left over after a collision between Earth and a Mars-sized body, is currently the most widely accepted theory explaining the origin of the Moon. This accounts for the Moon's composition and the Earth-Moon system's dynamics.

Question 17

Although we do not yet know precisely how the Moon was formed, an important clue is provided by the fact that:

Accepted Answer

Moon rocks resemble rocks close to the surface of Earth, suggesting that the Moon may have formed from debris resulting from a collision between Earth and another celestial body.

Question 18

Most of the craters on the Moon were created by:

Accepted Answer

The answer of Most of the craters on the Moon...

Question 19

Before the Mars-sized impactor struck Earth to cause ejecta that formed the Moon, Earth probably had a:

Accepted Answer

Before the impact that led to the formation of the Moon, Earth likely had a smaller density due to less compression and a slower rotation rate. The impact is thought to have increased Earth's rotation speed and contributed to its current density through redistribution and reformation of material.

Question 20

What difference, if any, would have resulted if the protoplanet that struck Earth had done so before Earth underwent chemical differentiation?

Accepted Answer

The answer of What difference, if any, would have resulted...

Quiz 10: Our Barren Moon