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Earth Formed from Diverse Meteorite Mix: Scientific American

Earth's building blocks were more eclectic than once thought, according to a new study suggesting our planet formed from collisions of many different types of meteorites.

Our planet is thought to have formed around 4.5 billion years ago from a disk of dust grains left over from the cloud of material that built our sun. These grains slowly clumped together, drawn by gravity into pebbles, then boulders, then planetary embryos. Eventually, enough mass coalesced to form the planet Earth.

Scientists had thought that most of the bodies that merged to make Earth formed from a narrow zone in space and were similar to each other, belonging to a subclass of meteorites called enstatite chondrites. This idea was based on measurements of numerous striking similarities between different types of atoms (called isotopes) of elements such as oxygen, nickel and chromium, between the Earth and enstatite chondrites.

But a new study of the silicon isotope signature of Earth rock samples and meteorites suggests that Earth is made of a more diverse mix of meteorites. [The Solar System To Scale (Infographic)]

The fact is that what we're experiencing right now is a top-down disaster. -Paul Krugman
by dvx (dvx.clt št gmail dotcom) on Sun Mar 4th, 2012 at 01:23:29 PM EST
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