Final answer:
The Moon's surface reflects a history of impact events due to its lack of an atmosphere. The giant impact hypothesis suggests the Moon formed from debris after a Mars-sized body collided with Earth. This scientific understanding complements human fascination with the Moon as explored through missions like Apollo.
Step-by-step explanation:
The Moon has undergone various changes throughout its history, primarily through impact events that shaped its current appearance. This is because the Moon, unlike Earth, does not have an atmosphere or active geology to erase the evidence of such impacts. The fission theory suggests that the Moon was once part of the Earth but became a separate entity early in their history. The most widely accepted theory today is the giant impact hypothesis, which posits that the Moon formed from the debris ejected when a Mars-sized body collided with the early Earth. This hypothesis is supported by increasing evidence that large planetary-mass objects were present in the inner solar system and could have resulted in such an event. The Moon's path across the sky and its phases can be explained by its motion relative to the Earth and the Sun, with phases of the Moon occurring due to its positions relative to the Sun, and not because of Earth's shadow. The exploration of the Moon, such as the Apollo missions, has provided a wealth of information and dispelled many earlier misconceptions, while also enriching our understanding and fascination with our closest celestial neighbor.