Astronomers have been wondering about the origin of the moon for many years. The most popular idea is the "high impact" idea. A large asteroid the size of Mars collided with the Earth and shaved off a gob of Earth that oozes into space and becomes the moon. But there are other stories. One idea states that the moon is a sister to Earth. This idea lost momentum when astronauts couldn't find any iron on the moon. Another idea is that the moon formed somewhere else in the solar system and then was captured by Earth's gravity and locked into Earth's revolution around the Sun. This idea was dispelled when moon rocks came back having the same composition as Earth's crust. And finally another idea formulated was that when the Earth was a hot ball of lava it was spinning so fast that a part of it was flung out into space. This idea was nixed because computer computations show that the Earth would have had to be spinning really fast and the evidence just isn't there to support this idea. Why is the "high impact" hypothesis the best? 1. The Earth has a large iron core, but the moon does not. This is because Earth's iron had already drained into the core by the time the giant impact happened. Therefore, the stuff blown out of both Earth and the large object came from their rocky surfaces. The iron core of the large object melted on impact and sunk into the iron core of Earth, according to computer models. 2. Earth has a density of 5.5 grams/cubic centimeter, but the moon has a density of only 3.3 g/cc. The reason is the same, the moon lacks iron. 3. The moon has exactly the same oxygen composition as the Earth, whereas Mars rocks and meteorites from other parts of the solar system have different oxygen compositions. This shows that the moon formed from material in Earth's neighborhood. Studies of lunar rocks show that the moon originally had a molten surface. As this so-called magma ocean cooled, intense volcanic eruptions continued for about 900 million years. This scene on the moon typifies the moon as it has been for about 3 billion years. Volcanism has ended. Meteorite impacts are rare. The quiet landscape awaits the return of human explorers. A good place to study this ongoing research is here: Planetary Science Institute https://www.psi.edu/epo/moon/moon.html
These scientists are constantly researching planets and moons in our Solar System.
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Mrs. TaylorI love science! Everything about the world is interesting and never boring. I love to study plants, animals, insects, and people. My favorite subjects are my students who are the most unique organisms on the planet! Categories |