Clues to Solar System's Early History Found in Ancient Meteorites
The makeup of a planet's innermost layer happens when a celestial body undergoes heat-related chemical processing that segregates certain elements - including osmium, iridium, ruthenium, platinum, palladium, and rhenium - into the core. But studies show that mantles of the Earth, Moon and Mars contain more of these elements than scientists theorize they should.
To study how these planets may have originated and what caused the imbalance in elements, scientists look to meteorites. A research team looked at diogenite meteorites that may have come from the asteroid Vesta or a similar body, either of which would be large enough to have similar chemical differentiation as Earth. The meteorites serve as a scale model of a terrestrial planet for their work, which is published in Nature Geoscience.
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The team examined seven diogenites from Antarctica and two that landed in the African desert. They were able to confirm that these samples came from no fewer than two parent bodies and that the crystallization of their minerals occurred about 4.6 billion years ago, only 2 million years after condensation of the oldest solids in the Solar System.
Studies indicate that the Earth's and Moon's mantles may have formed more than 4.4 billion years ago, and Mars's more than 4.5 billion years ago, reports The Daily Mail, so these meteorites are a good indicator of what was happening around that time.
They found that the timeline for the Earth's formation must have happened more quickly than previously thought. A planet must go through accretion - in which gravity pulls together matter in space to form a solid object - core formation, primary differentiation - where certain elements are layered into core and mantle - and late accretion. The team found that those were all completed in just 2 to 3 million years, after which the Earth formed its crust and developed an atmosphere and plate tectonics.
"This new understanding of diogenites gives us a better picture of the earliest days of our Solar System and will help us understand the Earth's birth and infancy," said Doug Rumble of The Carnegie Institution for Science, according to Zee News.
"Clearly we can now see that early events in planetary formation set the stage very quickly for protracted subsequent histories," he added.
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