The formation of the Solar System and planets
As you may remember when we talked about the formation of the Solar System in other courses or, if you are enrolled, in the subject of scientific culture in 4th ESO, there have been various theories about how the solar system and the Earth originated.
The currently most widely accepted theory is the nebular or planetesimal accretion theory.
According to this theory, the Solar System was formed about 5000 million years ago from a nebula, a large cloud of gas (mainly hydrogen and helium) and cosmic dust located at the end of one of the arms of the Milky Way, our galaxy.
The explosion of a supernova could produce an expansive wave that caused the particles to rotate and the nebula to contract, taking the form of a gigantic disk.
Most of the material is concentrated, by gravity, in the center of the disc resulting in a large mass of hydrogen and helium whose temperature rose to thermonuclear reactions that occurred fusion originated the sun.
The rest of the matter continued to revolve around the Sun, forming a flat disk. The gas and dust particles were condensing and coming together to form larger and larger bodies, the planetesimals. From the collision and fusion of different planetesimals during 400-450 million years, the planets arose:
- Four rocky inner planets: Mercury, Venus, Earth, and Mars.
- Four gaseous outer planets: Jupiter, Saturn, Uranus, and Neptune.
These impacts of planetesimals and meteorites continued to occur years after the formation of the Earth ( 4.5 billion years ago ), so it continued to increase in mass and temperature, which caused its fusion.
The fusion of the planet is the cause that the materials are distributed inside the Earth according to their density:
- Heavy elements, such as iron and nickel, formed the nucleus.
- Light elements. They formed the crust and mantle.
- Gaseous substances, such as carbon dioxide, water vapor, nitrogen, etc., came out of the interior of the Earth and formed the primitive atmosphere.
As the temperature of the atmosphere lowered, clouds were formed by the condensation of water vapor that produced enormous precipitations that cooled the earth's crust and originated the seas and oceans of the primitive hydrosphere.
Humor: Big Bang according to Peter Griffin.
Video: Evidences of the Big Bang. Origin and evolution of the universe . ElMonoDarwin.