A new computer simulation suggests that the Moon may have formed much more quickly than previously believed, offering an alternative explanation for its origin. The study, published in The Astrophysical Journal Letters, challenges the traditional view that the Moon formed gradually from a debris disk created by a massive collision between Earth and another planetary body. Instead, it proposes that a lunar-sized body could have been placed directly into orbit around Earth within just a few hours after the impact. The Moon has had a profound influence on Earth's environment, affecting tides, slowing Earth's rotation, and helping to stabilize its axial tilt. Scientists have long studied lunar rocks brought back by the Apollo missions, which show a composition very similar to Earth's. This similarity suggests the Moon did not form from material captured from elsewhere in the Solar System but rather from debris produced by a collision with another body. The widely accepted "giant impact hypothesis" states that about 4.5 billion years ago, a Mars-sized body called Theia collided with the early Earth, sending debris into orbit. This debris eventually clumped together to form the Moon. However, the new research suggests that under specific conditions, the collision could have directly placed a large body into orbit without the need for the debris to gradually accumulate. The researchers ran simulations that considered the mechanical properties of materials, which are affected by temperature. When Earth and Theia were cold and rigid, the impact could have preserved a chunk of Theia, allowing it to stay in orbit around Earth. In some of these simulations, the process occurred within five hours. The study tested different initial temperatures—approximately 400, 800, and 2000 Kelvins—and found that a rapidly formed Moon is physically possible under certain conditions, which previous models often overlooked. One lingering mystery is the similarity in isotopic composition between Earth and Moon rocks. Theia, being from a different region of the Solar System, was expected to have a different chemical makeup. One possible explanation is that Theia and the early Earth formed from similar materials in the same part of the protoplanetary disk. This study suggests the Moon's formation timeline may be shorter than previously thought, with the possibility that it appeared in Earth's sky almost as quickly as the collision that created it.