The moon famously has two sides, with a notably stark contrast between the heavily-pockmarked far side and the lower-lying open basins of the area facing Earth. And scientists now believe they have now solved the decades-old mystery over the origin of this difference. Newly re-examined evidence supplied by US space agency NASA has revealed a collision between the moon and another celestial object billions of years ago was responsible for the lopsided lunar surface. The new research suggests a collision between the moon we know today an ancient second orbiting body in the early solar system is the best explanation.
The difference between the Earth-facing near-side of the moon and the moon’s scabrous far side has been debated since the NASA Apollo era.
Scientists had previously thought Earth boasted two moons billions of years ago which merged, creating uneven surface seen today.
Measurements made by the NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission in 2012 supplied the extra data needed about the structure of the moon.
The topography is most prominent difference between the two sides.
There is a large basin area on the near side and on the far side you have the cratered lunar highlands.
But the main difference which showed-up during the NASA GRAIL mission, which showed the moon’s crust is much thicker on the lunar far side.
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The study’s co-author Professor Dr Kai Wünnemann explained to Express.co.uk what had been confirmed.
He said: “Even before the GRAIL mission it was proposed decades ago this basins on the lunar near side might have had an impact origin.
“And it turned out it was a bigger structure than we expected.
“The entire lunar near side may have been the consequence of a large impact and the highlands may have formed from the material that was ejected.”
The researchers discovered the best solution is a large body, about 480 miles (780km) across, slammed into the near side of the moon at 14,000mph (22,500kph).
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The model shows the impact would have thrown up vast amounts of material that would fall back onto the moon’s surface, burying the crust on the far side in 3 to 6 miles (5 to 10km) of debris.
Professor Wünnemann revealed the practical applications of the groundbreaking study.
He told Express.co.uk: “The research contributes to our understanding of the late accretion process.
“The moon was mostly likely formed from a giant collision with the Earth and this set the stage for everything that came afterwards.
“Following this scenario it was a big magma lump covered with a molten ocean.
“And it was hard to understand how Earth developed into a habitable world.
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“And what we now assume about the earth’s first billion years a lot more collisions continued to occur.
“And we believe this period actually changed the face of Earth, allowing Earth to develop to an atmosphere.
“Our theory gives us a better idea about the impactor flux, or their size.
“We don’t have any evidence for this on Earth, because the oldest terrestrial record doesn’t stretch that far back.
“But the moon is a better witness to this dark age because it has preserved these impacts.
“So in a way you could consider this study as one piece helping better understand this period that turned Earth into a habitable world.”