How is the moon formed? Discover the theories that explain how the moon originated

Have you ever wondered how the moon was formed? Our natural satellite has been orbiting the Earth for a few billion years, and scientists have already developed a few theories to try to explain the origins of the Earth-Moon system—among them, the most widely accepted describe that the Moon would have appeared after a large object collided with Earth. The impact could have destroyed part of the Earth’s mantle and moved material into orbit, forming the Moon.

Although many planets in the solar system have their own moons, Earth is the only one in our region that has a large natural satellite (compared to the size of the planet). In addition, the lunar influence on Earth’s cycles – especially the tides – has been studied by different cultures at different times.

Since the Moon is able to store information about the composition of the Earth and has a relatively stable surface, without wind or rain capable of erasing evidence of its geologic past, studying it is a way to better understand our planet.

But if we take into account the composition of the neighboring planets and the moon, there is something strange: our natural moon formed about 100 million years after the birth of the solar system; Therefore, if he was not born from the events that led to the formation of other planets, then scientists began to ask themselves: how did the moon arise?

How is the moon formed?

Various theories have been developed to try to explain how the moon was formed. One is the capture theory, which suggests that the moon formed elsewhere in the solar system and wandered through space, until it came close to Earth and was captured by our planet’s gravity, similar to what one of the researchers suggested. Theories explaining the possible origins of Mars’ moons Phobos and Deimos.

This scenario could explain the differences between lunar and terrestrial composition, but it leaves some questions open: Objects formed in this way are not spherical and their trajectories are not usually aligned with that of the planets; Therefore, it does not correspond to lunar characteristics.

On the other hand, accretion theory suggests that the Moon formed near the Earth; This would explain its current location, but not its composition. If the Moon was formed at the same time as the Earth, the Moon would have had a composition very similar to that of our planet, which is not the case: it is much less dense, a property that is difficult to notice if both were born with similar heavy elements in their cores.

Finally, we still have the fission theory, which proposes that the Moon came from a rupture in the structure of our planet; This would have happened in the past, when the primal earth would have rotated so fast that it would split into two pieces. The problem with this scenario is that the current Earth-Moon system must have had fossil evidence of such rapid rotation, which is not the case. Moreover, this hypothesis does not explain the heat that fell on the lunar material.

The most accepted theory of how the moon appeared

“There have been many theories about how the moon was formed, and one of the goals of the Apollo program was to find out how we got it,” explains Sarah Russell, a planetary science researcher at the National History Museum in the UK. “When rocks [missões] The Apollos returned, and they showed that the Earth and the Moon had some important chemical and isotopic similarities, indicating that they had a related history.”

One of the main goals of the program was to test the three prevailing theories, but in the end, data from the Apollo missions inspired the creation of a new theory. During the 1970s, researchers proposed what became known as the “giant impact hypothesis,” a new scenario in which a Mars-like object collides with Earth, expelling bits of vaporized Earth’s crust into space.

Then, gravity would have held the debris together, making up what became the solar system’s largest moon compared to its planet. This formation process explains why the Moon was formed primarily from elements that make it much less dense than Earth: the material that formed it would have come from the crust, leaving the rocky core intact. Then, as this material accumulated around the remainder of Thea’s core, it could have ended up near the ecliptic, where the Moon orbits the Earth today.

Despite being the most accepted theory today, it was initially met with skepticism by scholars. On the other hand, this new model seems to match several pieces of evidence: if the material that formed the Moon came from the outer layers of the Earth and Theia, then the expectation is that the Moon contains a low amount of iron – as observed in the measurements obtained remotely, indicating a lack of an element in our natural satellite.

The angle of impact of the object could have already caused the Earth to reach a high rotational speed. In addition, the energy of the event could have wiped out part of the projectile, which explains the absence of volatiles in the lunar composition. But even today, this theory also remains with some unanswered questions.

Most models of lunar morphology suggest that more than 60% of its composition must have come from material from Theia, but samples from the Apollo missions indicate that the Earth and Moon are roughly twins when it comes to composition. “This discrepancy overshadows the giant impact model,” notes Alessandra Mastrobuno-Batisti, an astrophysicist at the Israel Institute of Technology.

Source: via: Space.com (1And two), SciTech DailyAnd Natural History MuseumAnd NASAAnd astronomy.com