Deep In The Earth's Core, Clues About Its Mysterious Birth
Earth's Creation NASATo deduce how and when the Earth was formed, we need to know exactly what it's made of. We've known for over half a century that the Earth is 4.5 billion years old, but for people like University of California, Davis geologist Qing-zhu Yin, that number just isn't good enough--they need to determine what digit comes after the '5'. Yin has spent the last fifteen years trying to figure out exactly how our solar system formed--how, over a span of some tens of millions of years, a large chaotic disc of dust and gas turned itself into eight planets in orderly orbit around a central star. Scientists have come up with a couple versions of the story: in one version, Earth emerged from an era of meteoric collisions so intense that the entire planet was, at first, a spherical sea of magma. In another version, the process was...