Half-Baked Asteroids Have Earth-Like Crust

In the article, “Half-Baked Asteroids Have Earth-Like Crust”, it talks about how two meteorites were recently found during a search in Antarctica. What was unusual about these meteorites was their composition. The asteroid fragments were made up of andesite rock. Scientists had believed that due to the small size of asteroids, their crusts could be made up of only certain kinds of rock. This discovery has changed scientists’ perspective on asteroid formation. Andesite was found only on Earth near areas where tectonic plate collisions occur. Therefore, scientists thought that these meteorites might have come from a planet or the moon rather than an asteroid because they thought that the way andesite forms can not occur on an asteroid. However, after analyzing the oxygen isotopes of the samples, this assumption was impossible. It was determined that the meteorites came from asteroid 4 Vesta. These meteorites can help us learn more about our solar system’s history because they are more than 4.5 billion years old like the solar system. James Day, the lead author of the study, said, "Ultimately this may shed light on how evolved crust forms on planets, including Earth, during the earliest stages of their birth." I agree with Day and I think that the meteorites will not only tell us how crusts form, but also how certain asteroids can form.

http://www.sciencedaily.com/releases/2009/01/090107134526.htm