Challenging theories on the origin of Earth
For a century, scientists have assumed that the Earth’s chemical makeup is the same as the Sun. Now two Australian researchers have other ideas.
Professors Ian Campbell and Hugh O’Neill from the Research School of Earth Sciences at the Australian National University (ANU) have suggested that the Earth didn’t form from the same material (chondritic meteorites) as the Sun, as scientists had previously believed.
“For decades it has been assumed that the Earth had the same composition as the Sun, as long the most volatile elements like hydrogen are excluded. This theory is based on the idea that everything in the solar system in general has the same composition. Since the sun comprises 99% of the solar system, this composition is essentially that of the Sun,” Professor O’Neill said.
Instead, the ANU scientists think that Earth was formed through the collision of larger planet-sized bodies. In 20 years of studying mantle plumes (columns of hot rock that rise from Earth’s core), Professor Campbell discovered no evidence of “hidden reservoirs” of heat-producing elements such as uranium and thorium that had been thought to exist, if in fact Earth actually formed from chondritic material.
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