(ORDO NEWS) — In the very early years of the solar system, the formation of the Earth could take much less time than scientists thought.
According to an analysis conducted in February 2020, there is evidence that most of the Earth gathered in just 5 million years – several times less time than current models suggest.
This revision is a significant contribution to our current understanding of planetary formation, suggesting that the mechanisms can be more varied than we think, even between planets of the same type located in the same area – rocky planets such as Mars and Earth.
You see, we’re not 100% sure how planets form. Astronomers have a pretty good general idea, but the finer details … well, they’re pretty hard to see in action.
The broad strokes of the planetary formation process are associated with the formation of the star itself. Stars form when a lump in a cloud of dust and gas falls under its own gravity and begins to spin. This causes the surrounding dust and gas to circulate around it, like water circulating around a drain.
As it rotates, all of this material forms a flat disk that feeds on a growing star. But not the entire disk will be absorbed – what is left is called a protoplanetary disk, and it continues to form planets; This is why all the planets in the solar system are approximately located on the same plane around the sun.
When it comes to planetary formation, it is believed that tiny particles of dust and rock in the disk will electrostatically cling to each other. Then, as they grow in size, so does their gravitational force. They begin to attract other clusters through random interactions and collisions, increasing in size until they become a whole planet.
It was believed that for the Earth this process took tens of millions of years. But analysis of iron isotopes found in the Earth’s mantle suggests otherwise, say scientists at the University of Copenhagen in Denmark.
In its composition, the Earth differs from other bodies in the solar system. Earth, Moon, Mars, meteorites – they all contain naturally occurring isotopes of iron such as Fe-56 and the lighter Fe-54. But the Moon, Mars and most meteorites have the same number, while on Earth there are significantly less Fe-54.
The only other rock that has a composition similar to that of Earth is a rare type of meteorite called CI chondrites. The interesting thing about these meteorites is that they have a composition similar to the solar system as a whole.
The researchers concluded that since the protoplanetary disk and the large amount of dust in it that formed the Earth only lasted about 5 million years, the Earth must have emerged during this time period.
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