Scientists have a controversial theory about how and how quickly the Earth formed

in A new study was released In Nature this week, researchers report that Earth formed in just 3 million years. This is significantly faster than previous estimates that put the timeline up to 100 million years.

Millions of years may not seem fast to mere mortals, but on an astronomical scale, they are incredibly fast. During the 4.6 billion years of our solar system’s existence, 3 million years is the blink of an eye. This is the equivalent of less than a minute in a 24-hour day. (If Earth had formed over tens of millions of years, that would be the equivalent of 5 to 15 minutes a day.)

“Planets can go from their infancy to the size of Earth and Mars in just a few million years, which is really, really fast compared to the hundreds of millions of years previously thought,” said Isaac Onit, lead author of the study. and Ph.D. candidate at the University of Copenhagen. “We can also expect that if other planets formed…by the same mechanism, the ingredients required for life such as water, would have to be present on other planets and other systems, so there is a higher chance that water worlds exist elsewhere in the galaxy.”

The authors assert that this rapid formation occurred through a theory called gallstone accretion. The general idea, according to co-author and cosmochemist Martin Pizarro, is that planets are born in a disk of dust and gas. When it reaches a certain size, it quickly attracts those pebbles like a vacuum cleaner. Some of these pebbles are icy and could provide the Earth’s water supply, it is believed Pebble snow. This would have resulted in an early version of our planet, known as Proto-Earth, roughly half the size of our current planet. (Our current view of Earth likely formed after a larger impact about 100 million years later, which also led to the formation of our moon.)

However, this gravel accretion theory of Earth’s formation is controversial.

Scientists agree that this theory explains the formation of gas giants in our solar system, such as Jupiter and Saturn – the accumulation of gravel is the only way for a giant planet to grow fast enough before its planetary disk dissipates. But they are disputed relative to their terrestrial counterparts. others He pointed out the issues Where did the pebbles come from around the planet or why the planets aren’t bigger.

The most widely accepted theory, Onit says, is that terrestrial planets, like Earth, were formed through a series of collisions from asteroids that got progressively bigger and bigger. This process means that the Earth’s formation took about 100 million years or more. In this mechanism, the presence of water on Earth may have been fortunate, perhaps transported by an asteroid or comet.

Co-author Martin Schiller said he and his colleagues want others to rethink how terrestrial planets formed. “Yes, of course, pebbles are available everywhere. Of course, terrestrial planets will also grow by accumulating pebbles,” said Schiller, a cosmochemist at the University of Copenhagen.

Pizarro added that this study provides the “strongest evidence” that terrestrial planets formed through the accumulation of gravel.

The team determined the time scale of Earth’s formation by looking at silicon isotopes from more than 60 meteorites and near-Earth planetary bodies, which represent the debris left after the planet formed. Silicon is a major component of rocks and a vital building block for the planet, similar to carbon for life. Because they are so abundant in the universe, they are easily and commonly produced and can serve as a good tracker for planetary formations.

By analyzing the compositions of silicon in samples of different ages, Onyett said they can piece together a timeline of what was going on in the dust disk before Earth formed. They found that as the samples aged, the composition of the asteroids changed toward the formation of cosmic dust that was accumulated by Earth.

“This is very strong evidence that this dust was also being swept up as it drifted inwards toward the sun,” Onyet said. “It would have been swept away by the earth because it was growing in accumulation.”

Berger Schmitz, an astronomer at Lund University who was not involved in the research, said the findings are “very compelling” and could change the way we think about our planet’s formation.

“If these explanations hold (which I believe they will), this represents a major paradigm shift in our understanding of Earth’s formation,” Schmitz, a research associate at the Chicago Field Museum, wrote in an email. Paradigm shifts always come as big surprises…..how wrong we’ve been for so long!

More importantly, he said, the findings show that there is nothing special about our water-bearing planet. “It’s just a very ordinary planet in our galaxy. This is important in our attempts to understand how common higher forms of life are in the universe.”

The new research provided a fascinating analysis of the isotopic composition of silicon across many planetary materials, said radioisotope cosmologist François Tissot, who was not involved in the study. But he isn’t sure that grit buildup is the simplest explanation for the trends in the silicon data. He said additional analysis was needed as to how the new Si isotope data fit, or did not fit, other models.

Still, Tissot, of Caltech, said, “These are exciting results that will bring major new constraints to our understanding of Earth’s formation.” “It is an exciting time for the community and an undeniable step forward.”