The history of our Earth is long and complicated. The continental crust, which stretches miles deep, contains the historical account of our planet. Some of the oldest rocks are over four billion years old, while the younger ones are still forming to this day.
The data scientists collected shows a fascinating timeline of our ever-changing planet, and with this article I am planning to show you more of what earth looked like 4.5 billion years ago.
Although most planets surround considerable stars in their galaxies, how they actually form remains a subject of debate, even though there’s some proof at the edge of the Universe. Currently, two main theories are duking it out for supremacy.
The first one is the most widely accepted theory, called core accretion and works well with the formation of terrestrial planets like our Earth, but has problems with giant planets which are usually made up of gas, like Saturn. The second theory is called the disk instability method and it may account for the latter category.
The core accretion model
4.6 billion years ago, at the point where our journey begins, the solar system we live in was a cloud of dust, known as a solar nebula in the scientific community. Gravity then collapsed the material in on itself, it began to spin, and then it formed the sun in the center of the said nebula.
A few million years later, solar winds swept away light elements, leaving only rocky materials to create smaller terrestrial worlds like Earth. The planet’s rocky core was the first one to form, with heavy elements like iron colliding and binding together.
In its early stages, Earth suffered an impact when a large body collided with our planet, and it threw bits of it into space, where gravity transformed them into our Moon. Because the Earth’s outer core is liquid, its movements cause plate tectonics, a motion which gives birth to mountains and volcanoes, things that had the most impact on shaping the young planet’s surface.
Furthermore, meteorites, asteroids and other bodies from this category soon started to hit our surface just like they hit the Moon, and they most likely deposited the Earth’s water on its surface, thus shaping the planet even more. Some speculations say that’s how life came about, and that we are the descendants of the bacteria carried by those frozen rocks.
Exoplanet observations, mainly from space telescopes like Hubble, seem to confirm core accretion as being the legit theory. The 2005 discovery of a new giant planet with a massive core is another piece of the puzzle that helped NASA strengthen the case for core accretion.
Plus, all around the world, you can spot asteroid impact crates, filled with pieces of rock that are thousands upon thousands of years old and that resemble nothing on Earth.