Final answer:
The leading theory for the formation of Earth's Moon is the giant impact hypothesis, which suggests the Moon was created from the debris of a collision between Earth and a Mars-sized object.
Step-by-step explanation:
The leading theory for the formation of Earth's Moon is the giant impact hypothesis. This hypothesis suggests that the Moon was formed from the debris left over from a collision between the Earth and a Mars-sized object around 4.5 billion years ago. The collision produced a ring of debris around Earth, which eventually coalesced to form the Moon. This idea overcomes the issues posed by the other theories such as the fission, sister, and capture hypotheses.
Earlier hypotheses like the fission theory, suggesting the Moon was part of Earth, the sister theory, that the Moon and Earth formed together but independently, and the capture theory, where the Moon formed elsewhere and was later captured by Earth's gravity, have significant problems. The capture theory, for instance, is difficult to support because of the unlikelihood of Earth capturing such a large object and the compositional similarities between the Earth and the Moon that indicate a more closely linked origin. Therefore, the giant impact hypothesis is the most widely accepted explanation for the Moon's origin in the scientific community today.