New theories provide a clues to the origin of the moon

The Moon is mysterious. We can gaze upon it every night, yet still be so far from uncovering its secrets. This week, new studies were published detailing new theories about the Moon's origin and evolution. The Earth and Moon may have more in common than scientists originally thought. Moon rocks have a composition which is similar to that of our own planet. Scientists have developed two theories, the "great impact hypothesis" and the "late veneer" hypothesis which describe how the Earth and Moon were formed.

A new study by scientists from the Technion-Israel Institute of Technology and published in the journal, Nature, modelled that as the earth was forming, it was hit by many planets that were also still in the infancy of forming. The final collision would have been with a celestial body 10 times lighter than the earth, resulting in the formation of the Moon from scraps of collision debris. This is known as the "giant impact hypothesis", but there are still some issues with the theory.

Scientist and author of the study, Dr. Perets states that the composition of the Moon and the Earth, "are almost identical. This is one of the major challenges for this really beautiful giant impact hypothesis." But, if the pseudo-planet which hit the Earth was made of similar matter as the Earth, issues with the theory as solved.

An additional theory explaining specifics in the Earth's matter is the "late veneer hypothesis". According to this hypothesis, a long time after "the great impact" occurred, the Earth and Moon gained extra matter during a huge onslaught of meteorites, creating a veneer of foreign matter in the late stages of celestial development.

Interestingly, due to the Earth's larger field of gravity, the Earth should have accumulated any thicker "late veneer" of foreign matter than the Moon. Two unrelated Moon rock investigations from America and Germany discovered correlating ratios of matter in the Moon rocks and Earth which support this "late veneer hypothesis". The studies specifically looked at tungsten isotopes from the Earth and Moon rocks collected from the Apollo missions.

The "giant impact hypothesis" and the "late veneer hypothesis" actually support each other, as the American and German studies found that the Earth and Moon had the same composition prior to the meteorite onslaught. This congruous composition can be explained by an impact with a planetary made of similar matter as the Earth.

Source: BBC