Has the mystery of how the moon formed finally been solved? Scientists find new evidence our lunar satellite was created during a giant impact between Earth and a Mars-sized planet 4.5 billion years ago

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It’s a mystery that has gripped humanity for hundreds of years – how exactly did our moon come to be?

Since the 1970s, astronomers have suspected that our natural satellite was created when a giant protoplanet called Theia hit the early Earth (Gaia).

However, the nature of this collision and what happened immediately afterward have been a matter of debate, with some scientists suggesting that it created a massive cloud of debris that coalesced into the Moon over time.

Now, new evidence has been uncovered supporting the impact theory 4.5 billion years ago, as well as revealing a rather surprising fact about our planet.

A new study says the collision not only created the Moon, but also buried traces of Theia deep in Earth’s mantle, which eventually helped create Hawaii and Iceland.

Discovery: Scientists have found new evidence that the Moon was created during a giant collision between Earth and a Mars-sized protoplanet called Theia 4.5 billion years ago.  This also buried traces of Theia deep in the Earth's mantle (as seen after the impact).

Discovery: Scientists have found new evidence that the Moon was created during a giant collision between Earth and a Mars-sized protoplanet called Theia 4.5 billion years ago. This also buried traces of Theia deep in the Earth’s mantle (as seen after the impact).

Theory: Experts believe the dense material sank to the lower region of Earth's mantle, where it gathered together to form heavy blobs above our planet's core that still exist today (shown in the center of the image of Earth).

Theory: Experts believe the dense material sank to the lower region of Earth’s mantle, where it gathered together to form heavy blobs above our planet’s core that still exist today (shown in the center of the image of Earth).

Moon theories

Astronomers have long suspected that the Moon was created when a giant protoplanet called Theia collided with the newly forming Earth, a theory first proposed in the 1970s.

It says the massive impact created a huge cloud of debris, which merged into the moon.

However, until now, astronomers have been unable to explain how this left the Moon and Earth so chemically identical.

Later, two hypotheses emerged that could explain why the Moon is a chemical clone of Earth, but they predict radically different masses for Theia.

In one scenario, the two halves of the Earth merged to form the Earth-Moon system.

But the second hypothesis suggests that Theia was a small, high-speed projectile that collided with a large, rapidly rotating young Earth.

Researchers led by the California Institute of Technology said that these traces from a protoplanet the size of Mars were thousands of miles across.

They believe the dense material sank to the lower region of Earth’s mantle, where it gathered together to form heavy blobs above our planet’s core that still exist today.

Scientists reached their conclusion with the help of computer simulations aimed at explaining why… A massive anomaly deep inside the Earth.

There are two regions at the base of our planet’s mantle that are unusual and different from the rest of the layer.

One, known as large low-velocity provinces (LLVPs), lies beneath the African tectonic plate and the other lies beneath the Pacific tectonic plate.

Its existence was confirmed when geologists found that seismic waves slowed significantly at a depth of 1,800 miles (2,900 kilometers) in the two regions, which is different from other parts of the Earth.

Scientists believe that the material in these LLVPs is between 2 and 3.5% denser than the surrounding mantle.

These regions are important because they played a major role in how the mantle evolved, which in turn would influence the formation of supercontinents and Earth’s tectonic plates.

However, how they appear remains largely a mystery.

Realizing the theory of moon formation, lead author Qian Yuan and his colleagues came up with the idea that LLVPs could have evolved from a small amount of Theyan material that entered Gaia’s lower mantle.

To support this, they asked Professor Hongping Ding, from the Shanghai Astronomical Observatory, to explore this idea with the help of his pioneering methods in computational fluid dynamics.

After performing a series of simulations, Professor Ding discovered that after the moon-forming impact, a large amount of Theian mantle material – about 2% of the Earth’s mass – entered Gaia’s lower mantle.

After performing a series of simulations, Professor Ding discovered that after the moon-forming impact, a large amount of Theian mantle material - about 2% of the Earth's mass - entered Gaia's lower mantle.  This is shown in orange in the artist's image above

After performing a series of simulations, Professor Ding discovered that after the moon-forming impact, a large amount of Theian mantle material – about 2% of the Earth’s mass – entered Gaia’s lower mantle. This is shown in orange in the artist’s image above

He added that the impact appears to have been “the starting point of Earth’s geological evolution over 4.5 billion years.”

The researchers also calculated that this lunar rock-like material is likely iron-rich, making it denser than the surrounding Gaian material.

This, they said, is what caused it to sink to the bottom of the mantle and eventually form two LLVP regions that have remained stable despite 4.5 billion years of geological evolution.

He also points out that the Earth’s interior is not a “boring” uniform system, but is actually a mixture of materials that can be brought to the surface to form land masses like Hawaii and Iceland.

“Through careful analysis of a wide range of rock samples, combined with more accurate giant impact models and Earth evolution models, we can infer the physical composition and orbital dynamics of the primordial Earth, Gaia, and Theia,” said Dr. Yuan.

“This allows us to constrain the entire history of the formation of the inner solar system.”

Not only that, but because giant impacts are common at the end of a planet’s formation, scientists say similar variations in the mantle may also exist in the interiors of other planetary bodies in our solar system and beyond.

The new study was published in the journal nature.

THEIA: An ancient protoplanet that may have merged with the nascent Earth to form the Moon

About 4.45 billion years ago, 150 million years after the solar system formed, Earth collided with a Mars-sized body called Theia.

The collision created the Moon, but controversy has raged over what exactly happened during this event, and mystery continues as to why the Moon and Earth are so similar in composition.

Theia’s impact on Earth was so violent, the resulting debris cloud mixed well before settling and forming the Moon.

It is assumed that this cloud is composed of some terrestrial materials, which explains the similarity between the Earth, the Moon and other materials.

The colliding object is sometimes called Theia, after the mythical Greek Titan who was the mother of Selene, the moon goddess.

But one mystery still remains, revealed by rocks brought back from the Moon by Apollo astronauts: Why are the Moon and Earth so similar in composition?

Several different theories have emerged over the years to explain the similar fingerprints of the Earth and the Moon.

The impact probably created a huge cloud of debris that completely mixed with the Earth and later condensed to form the Moon.

Or it is possible that Theia is, coincidentally, isotopically similar to the young Earth.

A third possibility is that the Moon formed from terrestrial materials, not from Theia, although this would be an unusual type of impact.

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