The Earth Would Have Formed Much Faster Than We Thought

A formation in just a few million years

But in recent years, a new idea has caught on. That of a much faster formation in just a few million years, which is not about huge impacts, but a collection of small elements only a few millimeters. This theory was presented in an article published three years ago (see below). The Copenhagen researchers, authors of that earlier study, are now returning to this topic to constrain the nature of the material at the origin of the solar system’s telluric planets, particularly Earth and Mars, in order to determine how they formed.

In a new article published in the journal Nature, scientists used the isotope silicon-silicon isotopes as a tracer to understand the mechanisms of planet formation. They therefore analyzed the isotopic composition of more than 60 different meteorites and planetary bodies to observe the “genetic-genetic” connection that might exist between them.

growth due to dust accumulation

The results show that contrary to popular belief, chondrites and chondrites are not the building blocks of planets like Mars and Earth. On the other hand, it appears that these two planets have an association with differentiated asteroids that formed very early in the history of the solar system. This indicates rapid formation in less than 3 million years from collisional growth and accumulation of very small elements in the protoplanetary disk. According to the researchers, a star with a diameter of one hundred kilometers can therefore form very quickly from this disk of dust. Once that size is reached, growth continues by “sucking in” all the elements present nearby, including small particles of ice.

The presence of water is no longer a matter of luck

This new vision therefore has implications for the origin of water on Earth. In the most common hypothesis, the water would actually have been brought to Earth by the bombardment of water-ice-rich comets at the end of the planet’s formation. But the new theory proposed by the Copenhagen researchers, which questions the way the Earth formed, implies that the accumulation of water occurred during the rapid accumulation phase and therefore did not have a “distant” origin.

A consideration that is important because it dismisses the notion of “luck” implied in the hypothesis of water brought by comets and comets. On the contrary, the new theory suggests that water is an element intrinsically linked to the formation of terrestrial planets, whether in our solar system or elsewhere.

The initial phase of the formation of the earth took place much faster than previously assumed. The researchers came to this conclusion by measuring Ferfer isotopes with extreme precision.

Article by Nathalie MayerNathalie Mayer, published February 24, 2020

Random collisions of ever larger bodies over tens of millions of years. This is how astronomers have long imagined that our earth was formed. But work by researchers at the University of Copenhagen (Denmark) is now challenging this theory. The whole thing would have happened in just five million years.

Only ? There is no doubt about the size of the universe. And even on the scale of our solar system. Its age is estimated at around 4.6 billion years. If you boil it all down to 24 hours, the Copenhagen researchers’ findings suggest that the proto-Earth would have taken just a minute and a half to form. About five to fifteen minutes after the previously accepted idea.

The work of researchers at the University of Copenhagen is now leading astronomers to a different theory. “The starting point was dust. Millimeter-sized objects falling in the rain on a growing body and forming our earth in one fell swoop,” explains researcher Martin Schiller in a press release from the University of Copenhagen.

Water more common than expected?

The researchers draw this conclusion from the most precise measurements ever carried out on iron isotopes. They actually studied the isotopic mix of this element in various meteorites. Only one type of meteorite showed an Earth-like composition: CI chondrites. “If the process had been more random, we would not have identified a single type of meteorite, but a mixture,” Martin Schiller assures.

Other meteorites, for example from Mars, show that the isotopic composition of iron was different in the materials used at the beginning of our planet’s growth. No doubt because of the temperatures then prevailing in the neighborhood of our young SunSun. After a few hundred thousand years, our solar system cooled sufficiently for external CI chondrite dust to enter the proto-Earth accretion region.

“This dust dominates the composition of the Earth’s mantle. This is only possible when most of the older iron has already migrated to the core. And if the formation of this core – what the researchers call planetary differentiation – happened very quickly,” explains Martin Schiller. “This discovery not only clarifies the history of our solar system, but could also shed light on how planets form elsewhere in the galaxy.” »

“Water could be a simple by-product of planet formation”

“If our theory is correct, water could well turn out to be a simple by-product of planet formation. Which makes one of the main components of life – as we know it – extremely commonplace in our universe.

Formation of the Earth: One of the geochronometers was wrong

Earth and the solar system were born about 4.568 billion years ago. The events that followed are now in doubt as a new, revised downward assessment of the half-life of a radioactive isotope of samariumsamarium, one of the geochronometers used so far, has been dated, which was produced in the first hundreds of millions of years of its development. The planetary differentiation of Earth, Moon, Moon and Mars would have taken place faster and earlier than previously thought.

Article by Laurent SaccoLaurent Sacco published on 04/09/2012

This is not a question of the age of the earth and the solar system. But an article published in Science proves that we need to rethink the chronology of events during the Hadean on Earth, Mars, and the Moon. If you ask Wolfram Alpha to tell you all about the isotope samarium-146, he will tell you that it is radioactive and has a half-life long enough to date ancient geological processes, unlike carbon-14 and its half-life 5,730 years. Most importantly, the indirect connection with the abundance of neodymium isotopes that can be measured today makes it possible to date processes that took place at the beginning of the history of the solar system.

However, the figure of 103 million years given for 146Sm is wrong! According to a group of researchers using the Argonne Tandem Linac Accelerator System at Argonne National Laboratory in the United States, the true value of samarium-146’s half-life is 68 million years.

Not a revolution for the age of the solar system, but as for the established chronology of events that occurred inside the rocky planets during the first hundreds of millions of years, we must check the copy!

Thanks to samples of lunar rocks and Martian meteorites, as well as terrestrial rocks, we had estimated the dates of the differentiation of these planets, i.e. the formation of chemically well-separated cores and shells. By including the new value of samarium’s half-life, these differentiations would have occurred faster, and the ages estimated using other nuclear clocks converged, the researchers said.

Faster formation of the lunar mantle

Some of the oldest rocks in the world show signs of aging and geodynamic and geochemical processes that they witness. We can already give a first assessment, which is as follows.

Earth

A mantle process that formed some rocks in Greenland was thought to have occurred 170 million years after the formation of the solar system. The revised age of 120 million years is now more consistent with that determined by another core clock related to rocks found in Australia. This suggests that this process has affected the entire planet.
Similarly with rocks in Canada, from 287 to 205 million years after the formation of the solar system, we transition to a different process.

moon

The formation of the lunar mantle has been dated to 242 million years after the formation of the solar system. The revised age is now 170 million years.
A lunar rock was recently dated using three atomic chronometers, one of which was Samarium 146. The ages taken from the other two clocks matched, while the age estimated by Samarium 146 differed. The revised version of Samarium 146 Half-Life has solved the mystery.