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Illustration of stage in the formation of the Earth-Moon system. The Earth was recently formed (4,600 million years ago) when it was struck by a large protoplanet, sometimes called the one, approximately three times larger than the mass of Mars. | Credit: Mark Garlik/Library for Scientific Photos/Getty Images
The moon is strange. This is completely unlike anything else in the solar system. So how did our planet end up with such a special moon? The answer is that, surprisingly, the moon is a piece of our planet.
It happens with the moon. For starters, it exists, which is strange in its own way. Mercury has no moons or Venus. Mars has two moons, but they are really just captured asteroids. Earth is the only rocky planet in the solar system with a significant moon.
And the moon is really significant: approximately 1.2% of the Earth’s mass. This may not be great in absolute sense, but for the solar system it is huge. No other moon is so big about his parent planet.
The oddities do not stop there. The total angular impulse of the rotation of the Earth, the rotation of the moon and the orbit of the moon are very large – far higher than for any other terrestrial planet. So how did we get so much inertia?
Plus, the moon is full of “kreeps”-that own potassium (K), rarely earth elements (REE) and phosphorus (P). These elements usually do not like to hang together, but lunar samples indicate that they are often mixed. This requires that the moon was melted at some point, which takes a lot of energy.
And the real cherry on the cake is that the moon has many of the same abundance of stable isotopes as the Earth does, which shows that the Earth and the moon have evolved from the same lump of material.
The leading explanation for all these mysteries is known as the hypothesis of giant impact. According to this story, when the solar system was just beginning, a protoplanet with the size of Mars named those bumped into the proto-earth.
Works of the art of the young Earth Moon system. The Earth was recently formed when it was struck by a protoplanet, called the one about three times larger than Mars. | Credit: Mark Garlik/Library for Scientific Photos/Getty Images
With an impact speed of about 20,000 miles/h (32,000 km/h) – relatively slow when the impact goes – what happened further was nothing but catastrophic. The heavy nucleus of thea sinks deep into the ground, expanding the core of our planet. The mantle of the two bodies mixed and thus accumulated our planet. And the crusts were scattered far into space.
What happened further is a little difficult to follow and depends a lot on how exactly the impact develops and what it is made of. But the overall picture is that some things fly away, never come back. Other things were raining on the earth’s surface. And much remained in orbit. In just a few hours – or maybe until a century or more – this material blends into its own solid object: the moon.
Some models suggest that a second moon, just a few hundred kilometers away, is formed along the far side and then slowly approached the moon and ignited. This would explain why the far side of the moon is more awakened on the near side.
There is also the opportunity not to be low-energy at all, a look at a look-Insight, this prototer was turning really quickly and then it was nailed by the one. This would deliver more than enough energy to evaporate everything and create a plasma -shaped ring known as the Blue.
No matter what, this impact releases a lot of energy – more than enough to turn the moon into a molten ball, more than enough to collect the elements of Kreep, and more than enough to mix the original material on Earth and the one to create a set of common characteristics between the earth’s crust and the moon.
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-Ancient impact that formed the Earth’s moon probably was one or two strokes
As with all hypotheses, this is not perfect. For example, if there is enough energy to liquefaction the moon, there is enough energy to liquefy the earth’s surface. But there is no evidence of large -scale magma seas in the history of Earth. Also, the moon has some volatile elements, such as water trapped in a rock-but giant impact, a giant energy event had to get rid of them.
Despite these warnings, the hypothesis of a giant impact is the most captivating story we have about how the moon is formed. And without a time machine in our distant past, we will never be able to prove it. But it still responds to almost all the evidence we have so far, so this is a story that is worth holding around.