According to one theory, Mercury was created after a giant asteroid collided with an even larger object about 4.5 billion years ago. This collision created the planet now known as Mercury and also shot a large amount of debris into space.

This idea that Mercury was the result of a collision was stemmed from the fact that the rocky planet has an unusual amount of metal for its size. Apparently after the impact, the outer layers were stripped off and very little of those outer layers reattached, thus creating a very thin shell and a dense core. Scientists have examined the apparent collision with the aid of computers and looked at the anatomy of the collision, as well as how some of the impact debris ended up on Venus and Earth. Earth’s moon was also the result of an impact, as was Pluto and its moons.

After examining the computer simulation, scientists were able to able to follow the formation of Mercury and determine the composition of the two colliding bodies, as well as follow the fragments that were the result of the collision for millions of years until they either came into contact with a planet, the sun, or were ejected from the inner solar system. This is how they were able to determine that some of the ejected material landed on Earth as well as Venus. The simulation also determined that it would take 4 million years for only half the particles to land back on Mercury, if they all fell back but by that time the debris would have been carried off by solar radiation which explains why Mercury didn’t keep much material on its outer shell.

Many planets and articles in space were created as a result of collisions. Dust in the early solar system became rock and eventually the planets we know today. Scientists believe many objects collided and became one larger object, while others were disintegrated or became dramatically altered after as much as a glancing blow. Planets may lose their crust, or atmosphere, or can be ripped apart to form smaller objects, or moons to other planets. These impacts create fragments that could become the space rocks that land on Earth today. The moon was thought to have been created when a mars-sized object slammed into our planet.

The solar system was created shortly after the Sun’s formation about 4.6 billion years ago. Scientists believe that the dust and gas that orbited the Sun gathered to form rocks. Those rocks collided and joined to form comets, and asteroids, and eventually planets. Scientists believe there may have been as few as 100 or so objects no larger than the Moon or Mars responsible for forming our planets, but their cosmic collisions would have created dramatic results. When gravitational forces are taken into account with massive objects even passing near each other, extreme changes to both bodies can take place. Each object can be decompressed, melted, lose material or even completely destroyed. The smaller object’s gravity could easily depressurize in the presence of a larger object causing the smaller of the two to break apart. This can cause the formation of asteroids and meteorites.

What’s left of Mercury after this apparent hit-and-run collision is a large and dense core surrounded by a very thin mantle and crust; however scientists still don’t fully understand the complexities of this theory, and are still examining it with the help of computer models and simulations.

The hit-and-run theory may however explain the extremely diverse composition of asteroids, including pieces that fall to Earth as meteorites. Some resemble the rocky surfaces of planets, but others are filled with iron, which is much more like the core of a planet. This diversity would account for the theory that all space rock was not formed in the same disk of debris; rather it has been formed as a result of many different collisions in space and therefore contains different types of material.

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