The most difficult piece of evidence to refute a same origin event like that described in the Giant-Impact Hypothesis is the fact that terrestial and lunar rocks contain the same ratio of stable isotopes ³.

Moreover, samples from the Moon have revealed that it was once an ocean of molten matter, though the extent of this is unknown. This phenomenon would have required an enormous amount of energy, far more than can be generated by accretion alone. Only a grand and energetic event, such as a giant impact, could have supplied such energy.

Adding to this, the Moon is found to have a small iron core, with a lower density than Earth. Computer simulations of a giant impact between a body the size of Mars and Earth indicate that the impactor’s core would penetrate Earth and fuse with its own core. Thus, it is evident that extraterrestrial bodies would have less metallic iron than other planetary bodies.

It is also noted that the Moon is depleted in volatile elements compared to Earth. These elements vaporize at comparatively low temperatures, and are easily lost in high-energy events. The Moon’s smaller gravity would have prevented them from being recaptured, unlike Earth.

Debris discs, similar to the Moon, have been observed in other star systems, adding to the validity of the Giant-Impact Hypothesis. Additionally, giant collisions are found to be consistent with the leading theory for the formation of the Solar System.

Despite this impressive array of evidence, there are still many questions that remain unanswered regarding the Giant-Impact Hypothesis ⁴. For example, the energy from the grand impact is believed to have heated Earth to the point of forming a global magma ocean, and there is evidence of the subsequent differentiation of heavier materials into Earth’s mantle ⁵. However, there is no self-consistent model that begins with the grand impact and follows the evolution of the debris into a single Moon. Other unresolved questions include when the Moon lost its share of volatile elements and why Venus, which experienced grand impacts during its formation, does not host a similar moon.

Other hypothosis presented as plausible have been generally ruled out as possible until one or more the findings mentioned above can be refuted with strong scientific merit ⁶.

In conclusion, the Moon remains a captivating enigma that continues to inspire and challenge the human imagination. The Giant-Impact Hypothesis provides a compelling explanation for the origin of the Moon, but much work remains to be done to fully unravel the mysteries of our celestial neighbor.