A New Perspective on Earth's Formation: The Speed of Creation
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Chapter 1: The Birth of Our Planet
The Earth originated from a swirling cloud of dust and gas surrounding the early Sun, known as a protoplanetary disk. This process, alongside the formation of other celestial bodies, occurred roughly 4.55 billion years ago. However, scientists from Københavns Universitet are reexamining this timeline, disputing the longstanding belief that Earth's formation unfolded gradually over a span of 50 to 100 million years.
According to the previously accepted model, our planet began as a planetesimal—a small planetary nucleus. It gradually grew into a protoplanet, attracting nearby matter, including other planetesimals that varied in size from tens to hundreds of kilometers. This slow accumulation was thought to take tens of millions of years, culminating in Earth's current form.
However, researchers Martin Bizzarro, Martin Schiller, and Isaac Onyett argue otherwise. Their paper published in Nature presents evidence suggesting that Earth's formation was a rapid process. They analyze meteorites for isotopes that briefly existed during the formation of the Sun and the protoplanetary disk.
This latest research focused on silicon isotopes found in over 60 meteorites. Their findings, combined with prior studies on iron isotopes, lead them to conclude that Earth wasn't the result of slow assimilation of other planetary bodies. Rather, it formed through the swift accumulation of millimeter-sized cosmic particles. In geological terms, we can envision Earth as a massive entity built from coarse sand and gravel.
“It happened almost instantaneously. If we imagine the solar system's formation as a 24-hour event, Earth's formation would occur in just a few seconds. At some point, the young protoplanet acted like a vacuum cleaner, drawing in all surrounding cosmic material. It achieved its current size in less than 5 million years,” explains Bizzarro.
Section 1.1: Water on Earth from the Start
The implications of this rapid formation extend to the existence of water on Earth. According to the study's authors, our planet was already a water-rich globe at its inception.
“There were ice crystals in the protoplanetary disk. Earth's 'vacuum cleaner' pulled them in as well,” Bizzarro states. This challenges the existing theory that water was later delivered to Earth by comets and other icy celestial bodies.
“If this were true, it would mean we were incredibly fortunate to receive a water supply from space,” adds Schiller. “Instead, our research indicates that water is a byproduct of the rapid formation of planets like Earth. Consequently, many similar worlds may exist outside our solar system. In essence, any planet orbiting a Sun-like star at the right distance could have water, at least during its formation.”
The findings align with a hypothesis that has been around for over 25 years, supported by some geologists. Studies of zircon crystals, over 4 billion years old and discovered in the Jack Hills of Western Australia, suggest that Earth was a hospitable planet almost from the outset, rather than a fiery, magma-covered mass that cooled for eons. The elemental traces found in these ancient zircons imply that oceans may have already existed on Earth over 4.4 billion years ago. If true, this indicates that water appeared very early on, and the process of Earth's formation was much quicker than previously thought.
Chapter 2: The Life Cycle of Planets
Do dying stars only bring about destruction? Until now, it was assumed that planets perish alongside their stars. However, new observational data...
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