Have you ever stopped to wonder where Earth's moon came from? The Big Splat Theory has been the most common and widely held explanation of the Moon's origins. It proposes that our planet's satellite was the result of an ancient planetary collision. New studies have made the Big Splat increasingly bizarre.
The conventional Big Splat Theory
Approximately 4.6 billion years ago, a space body about the size of Mars crashed into the Earth. The collision merged the body, known as Theia, with the Earth and threw debris into the planet's orbit. Over the millennia, gravity pulled the debris together, which formed the Moon as we know it today. The Moon formed approximately 4.5 billion years ago. The conventional Big Splat is supported by the fact that the moon is lacking in elements like zinc, lead, sodium and potassium. All of these elements are thought of as being volatile elements, so they evaporate and dissipate faster in events like the Big Splat collision. Their absence thus supports the theory. The theory is also supported by the Moon's iron core, which mirrors that of the Earth as expected.
Contradicting the theory though is the absence of isotropic fractionation. This phenomena results from lighter isotopes turning to vapor faster than heavier ones. The Moon should have large concentrations of these heavier isotopes, but it does not. The isotope concentrations are nearly identical to those of the Earth, particularly with oxygen and titanium, which should not be the same.
Two new Big Splat models
Some scientists now believe that the object colliding with Earth was actually substantially larger than Mars. Whatever collided with out planet was actually about the same size and mass as Earth and the impact was not just a singular crash. This expansion of the Big Splat involves a symmetrical collision. The first impact between the two bodies was a low-velocity impact and they sprung back apart only to crash together again within twenty-seven hours. With the second impact the two objects merged to form a singular entity as with the conventional theory. Surrounding the new Earth were the same particles and debris, which eventually come together to form the Moon.
The second new study is the much the opposite of the first and actually involves an object smaller than Mars. The smaller body collided with the Earth at a ridiculously high velocity. What follows is essentially the same as the conventional Big Splat, but it assumes an incredibly fast-spinning Earth, which was until recently thought to be impossible. It takes into account the steady decrease in Earth's spinning velocity over the last several billion years.
Both of the new models incorporate an Earth spinning at least twice as fast as it was once believed to be possible. Over the last 4.5 billion years the Moon has been getting farther away from the Earth and the Earth has been gradually spinning at a slower and slower velocity. If the Earth were originally spinning at this ridiculous fast rate it would be slowed substantially by gravitational interplay between the Sun and the newly formed Moon. This new concept is called evection resonance and resulted in the aftermath of whatever was involved in the Big Splat.