Question

The Moon is thought to have formed shortly after the formation of Earth, and therefore the age of the Moon is comparable to that of Earth. The surface of the Moon is covered by ancient craters formed by impacts of small solar-system objects such as meteoroids, but the surface of Earth shows no such craters. (10 points; 5 for each correct choice)

Which two statements are valid explanations for this observation?

A.) The Moon shielded Earth from impacts in the early solar system.

B.) Solar-system objects are more likely to impact satellites than planets.

C.) Geologic activity on Earth's surface has destroyed evidence of impacts.

D.) The Moon has a very thin atmosphere, eliminating erosion due to weather.

Answer 1

The lack of ancient impact craters on Earth compared to the Moon is due to Earth's active geology erasing impact evidence and the absence of atmospheric erosion on the Moon, which has preserved its craters. Therefore, the correct option is C & D.

Step-by-step explanation:

Two valid explanations for why Earth's surface does not show the same number of impact craters observed on the Moon's surface relate to the geological activity on Earth and the differences in atmosphere. The Moon and Earth were both formed around 4.5 billion years ago, but they have very different surface histories.

The first correct explanation is C.) Geologic activity on Earth's surface has destroyed evidence of impacts. Earth's active geology, including processes like plate tectonics and volcanism, has resurfaced the planet over time, erasing many signs of the ancient impacts that are so visible on the Moon.

The second correct explanation is D.) The Moon has a very thin atmosphere, eliminating erosion due to weather. Unlike Earth, the Moon lacks a significant atmosphere that could drive weathering and erosion processes, meaning that the impact craters have remained largely unaltered over vast spans of geological time.