The formation of the Moon has been one of astronomy's most enduring puzzles. The traditional view, known as the giant impact hypothesis, proposes that a Mars-sized body called Theia collided with the early Earth approximately 4.5 billion years ago. The debris from this cataclysmic impact eventually coalesced to form our Moon. This theory accounts for the Moon's relatively small iron core and its chemical composition, which closely resembles that of Earth's mantle. However, recent isotopic analysis has challenged this view. Samples returned from Apollo missions reveal that the oxygen isotope ratios of lunar rocks are virtually identical to those found on Earth — a finding that would be extremely unlikely if Theia came from a different region of the solar system.