How was the Earth formed

The formation of the globe

It is difficult to know when the Earth was formed for the first time, because there were no rocks left from the early days of the planet, but most researchers believe that the Earth was formed through a series of collisions that occurred less than 100 million years after the solar system coalesced, and according to most models of Earth formation More than ten collisions accompanied by other bodies added size to the growing planet, and scientists estimate that the Earth was cemented 4.54 billion years ago, by measuring the age of rocks on the surface of the moon and the age of meteorites on Earth.

Earth formation models and hypotheses

central accumulation model

About 4.6 billion years ago, the solar system consisted of a cloud of dust and gas known as the solar nebula, and gravity caused the material to collapse on itself during its rotation, which led to the formation of the sun in the center of the nebula. Gravity formed larger grains, and the solar wind drove away light elements such as hydrogen and helium and left rocky, heavy materials in the nearer regions of the sun.

The earth's rocky core was formed first, through the movement of tectonic plates, the sinking of dense materials towards the center, and the survival of lighter materials on the surface, forming the earth's crust. Collisions and friction led to the formation of mountains and volcanoes, and the emission of gases into the atmosphere.

The ignition hypothesis

The asteroids collided with other bodies, forming larger bodies, and over time they reached a hundred kilometers or so in size, and the energy of the collision was massive enough to melt and vaporize many materials, and the rocks, minerals, and iron separated themselves into layers, as the dense iron settled in the center The lighter rocks enveloped the layer of iron, forming a miniature model of the Earth and the other inner planets. Planetary scientists call this process differentiation.

The sun ignited at some point during that, and although its radiation was two-thirds of what it is now, the ignition process was sufficient to remove the gaseous part from the protoplanetary disk, and then the pieces of rocks, blocks, and asteroids continued to gather to form large and stable bodies in orbits far from Some of them have certain distances, and the Earth was one of these bodies, and studies on other planets show that these effects and strong evidence contributed to the catastrophic conditions on the beginnings of the planet Earth.

Stages of the development of life on Earth

The earth passed through many stages and historical events during its formation and development, which are as follows:

4600 million years ago: Earth formed.
4500 million years ago: The earth's core and crust were formed, as the heavy metals sank towards the center of the earth, forming the core, while the outer layer cooled and solidified, forming the earth's crust.
4400 million years ago: It formed the first ocean on Earth, through volcanoes releasing water vapor into the atmosphere, and then it fell in the form of rain and formed the first oceans on the surface of the Earth.
3850 million years ago: The first life appeared on Earth, as it was a very simple, single-celled organism.
1500 million years ago: The accumulation of oxygen in the Earth's atmosphere, as it was produced by cyanobacteria as a result of the process of photosynthesis.
700 million years ago: The first animals to evolve were simple, single-celled animals.
530 million years ago: The first vertebrates evolved in the form of fish.
400 million years ago: The first plants evolved.
350 million years ago: The first terrestrial vertebrates evolved as primitive amphibians, and later reptiles.
225 million years ago: The first dinosaurs evolved from lizards.
65 million years ago: Dinosaurs and many other creatures became extinct.
130 thousand years ago: The evolution of modern man.