The Moon shines on us. Now we are shining a light back


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The Independent Online

The origin of the Moon has fascinated humanity for as long as we have gazed at the night sky. Mythological interpretations of its birth have long since been replaced by more scientifically sound theories, and now, it seems, one in particular has come to the fore.

For the second time in less than a week, scientists have found evidence to support the idea that the Moon came into existence following an almighty collision between the Earth and an object the size of Mars around 4.5 billion years ago, soon after the Earth itself was formed.

The latest study reveals that there are chemical isotopes deep within the Earth’s mantle – the bit separating the molten iron core from the rocky crust – that could be the primordial signature of the ancient, pre-collision planet. This follows the news last week that scientists had found evidence for the Mars-size object, called Theia, buried in the chemical isotopes they have analysed in the lunar rock samples brought back to Earth on the Apollo missions.

Scientists had been unable previously to find substantial isotopic differences between lunar and terrestrial rock. This called into question whether the Moon was indeed created in a collision rather than comprising bits of the primordial Earth that had been flung out into orbit during its early formation.

The other 150 or so moons in the solar system are either captured lumps of rock or matter spun out from the planets that they orbit. No other moon seems to have been born from a major impact.

We owe so much to the Moon that its history deserves to be known. We would have no tides, no lunar influences on the many life-forms tied to the Moon’s cycle, and no poetry and songs celebrating the joy and sadness of a moonlit night – not forgetting werewolves and vampires. The Earth would quite literally be a different planet without its Moon and now it appears that we have come close to knowing how the Moon came into existence.

We can now look at the Moon in a new light. The orb in the night sky is not just any old moon, it’s the child of a cosmic bang that changed the Earth for the better.