The comet impacts the continents formed when the solar system entered the arms of the Milky Way

New research by Curtin has found evidence that Earth’s early continents were hit by comets as our solar system moved in and out of the Milky Way’s spiral arms, upending traditional thinking about how our planet formed.

The new research, published in Geologychallenges the existing theory that the Earth’s crust was formed solely by processes within our planet, shedding new light on Earth’s formative history and our place in the cosmos.

Lead researcher Professor Chris Kirkland, from the Timescales of Mineral Systems group at Curtin’s School of Earth and Planetary Sciences, said studying minerals in the earth’s crust has revealed a rate of crust production every 200 million years which corresponded to the transit of our solar system through areas of the galaxy with a greater density of stars.

“The Solar System orbits the Milky Way, passing between the galaxy’s spiral arms approximately every 200 million years,” Professor Kirkland said.

“Examining the age and isotopic signature of minerals from the Pilbara craton in Western Australia and the North Atlantic craton in Greenland, we find a similar rate of crustal production, which coincides with periods when the solar system has traversed areas of the galaxy most populated by stars.”

“As they passed through regions of higher star density, comets would have been dislodged from the far reaches of the solar system, some of which hit Earth.

“The increased impact of comets on Earth would have led to greater melting of the Earth’s surface to produce the floating cores of the first continents.”

Professor Kirkland said the findings challenged the existing theory that crust production was entirely related to processes internal to the Earth.

“Our study reveals an exciting link between geological processes on Earth and the movement of the solar system in our galaxy,” Professor Kirkland said.

“Linking the formation of the continents, the land masses on which we all live and where we find the majority of our mineral resources, to the passage of the solar system through the Milky Way sheds a whole new light on the formative history of our planet and of its place in the cosmos.”

Professor Kirkland is affiliated with the Institute for Geoscience Research (TIGeR), Curtin’s flagship research institute in the earth sciences.

Researchers from the University of Lincoln, the Astromaterials Research and Exploration Science Division of NASA’s Johnson Space Center and the Geological Survey of Western Australia also contributed to the study.

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Materials provided by Curtin University. Original written by Lucien Wilkinson. Note: Content may be edited for style and length.

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