Learning How The Moon Formed
With the recent blood moon, you may be wondering how that big sphere of rock came to orbit the Earth. It turns out that astronomers do not have any definite answers, but a recent report by the Israel Institute of Technology shows that the data is backing up one of the major hypothesis of how the Moon formed. Called “the giant impact hypothesis,” it posits that a Mars sized protoplanet or asteroid likely collided with Earth sometime 20 to 100 million years after the Solar System coalesced and the resultant debris eventually formed the Moon.
The issue with this theory is that the Moon should contain a large amount of the impacting protoplanet, called Theia, but instead seems to be composed of material very similar to that on Earth. Theia should have been broken apart and the Earth should have sustained damage, each contributing material, but according to mineral samples it seems that the Moon is nearly identical to Earth, or that the Moon formed without any extra protoplanet material.
Using computer simulation, the researchers at the Israel Institute of Technology ran a battery of tests to determine how difference sizes and shapes of Theia could result in different compositions of the Moon. They found the twenty to forty percent of the time, the mineral makeup of the colliding protoplanet was similar to that of the planet it collided with. In short, how the moon formed is so similar to the way it happened for the Earth because there is reasonably high chance that the colliding bodies are also similar.
The likelihood of this type of impact is increased because the two bodies are orbiting the Sun at a similar distance. This means that they will be incurring a similar amount of heat and thus may have equal amounts of different elements. It is therefore not surprising that two bodies with similar compositions collide and form a third body that takes from both. What the study does is tease out these statistical possibilities, which in turn leads more support to the giant impact hypothesis of how the Moon formed. You can read the full report here, included a detailed summary of isotope findings, which was published by Nature on April 9th.
There is nothing like a starry night sky, but the moon is certainly a hogger of the night sky’s spotlight: