A new study suggests that at the beginning of the Solar System, the Earth might have been formed faster than previous claims.
Based on a February 2020 study from the Centre for Star and Planet Formation (StarPlan) at the Globe Institute at the University of Copenhagen, our home planet was apparently formed within five million years. The new time frame is a lot shorter than previous estimates of anywhere from 16.7 to 50 million years. Evidence points out that the early proto-Earth came about extremely fast, "on an astronomical scale," as explained by the researchers.
From a 24-Hour Perspective
To put things in perspective, if the entire history of the Solar System were to be compressed in a 24-hour period, Earth was formed within 90 seconds. Previous estimates regarding the Earth's formation is equivalent to 5 to 15 minutes.
It is also in contrast to previous theories explaining Earth's formation through the random collision of larger planetary buildings over a longer time frame. The StarPlan study theorizes that the precursor to The Pale Blue Dot was formed through the rapid build-up of cosmic dust.
"We start from dust, essentially. Millimeter-sized objects, all coming together, raining down on the growing body and making the planet in one go," lead author and associate professor Martin Schiller said. Schiller also added that this theory of rapid planetary formation is "interesting to assess how likely it is for planets to form" outside our own solar system.
One theory proposes that stars are formed when space dust and gas clump together and later collapse on itself because of its gravity. It starts spinning and pulls more dust and gas to swirl around it. However, not all materials are taken by the now-growing star. Other materials swirl in itself, forming protoplanetary discs, which later becomes planets themselves. It explains why all planets in the Solar System appear almost aligned in a flat plane as they revolve around the Sun.
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Analysis of Iron Isotope Samples
Rock samples from meteorites in the hundred-milligram range were taken, extracting iron samples. Iron isotopes were measured through the multi-collector - inductively coupled plasma mass spectrometry (MC-ICP-MS) at Denmark's Natural History Museum.
Iron isotope samples were introduced to a plasma source through a stable introduction system (SIS). The University of Copenhagen research team then identified a material found in both meteoric materials and Earth-native materials - CI chondrites.
Other samples in the study, such as those from Mars, yield an iron isotope slightly different from the ones found on Earth. It was credited to the thermal processing of space dust around the early developing Sun.
"This added CI dust overprinted the iron composition in the Earth's mantle, which is only possible if most of the previous iron was already removed into the core. That is why the core formation must have happened early," Schiller explained. The lead author added that this mixture of materials could not have been possible if the planetary formation process was achieved through the repeated and random collision of other bodies.
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The study from StarPlan was supported by the Danish National Research Foundation as well as the European Research Council. Various meteorites, similar to the samples taken for the study, are on display in the StarPlan exhibit "Meteorites - Journey Through Time and Space," up until August 30.
