By gazing into slices of primitive meteorites, planetary scientists have reconstructed the tumultuous early days of the Solar System, when huge shock waves boiled and then froze minerals in the swirling cloud of dust around the newborn Sun. These molten mineral aggregates, called chondrules, accreted with other materials to form carbonaceous clondrites-a type of nonmetallic meteorite-during the first two to three million years of the Solar System's formation. Such meteorites still fall to Earth, providing direct evidence of conditions from 4.6 billion years ago. Isotope geochemist Nicole Xike Nie of the Massachusetts Institute of Technology studies the chemical composition of the chondrules to identify minerals that were present in the nascent Solar System and to hypothesize about the environment in which they formed. "In the early Solar System, there were a lot of chondrules floating around," Nie said. "But we don't know how they were formed. That question has been there for maybe more than 50 years."
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