history of the earth, pangea, extinction of the dinosaurs, extinction of the dinosaurs, history of the earth, documentary, dinosaur documentary, history of the universe, earth documentary, history of the earth, universe documentary, the earth after the dinosaurs, dinosaur documentary, extinction of the dinosaurs, dinosaurs, prehistory documentary, prehistoric earth, prehistoric animals, scientific documentary, world of dinosaurs, before the dinosaurs, before the dinosaurs, after the dinosaurs ------------------------- ???? History of the Earth: The history of the Earth begins from the first seconds of its formation. It has been developing for almost 4.6 billion years. Marked by mass extinctions, catastrophic episodes but also periods of stability, the Earth never stops evolving. Mysterious blue planet in the universe, it is the only one known today that houses a human life form. 4.54 billion years ago, the accretion of the Earth began with the formation of the Sun. A few million years earlier, the gravitational collapse of a tiny part of a molecular cloud gave rise to our star. A disk of gas and dust formed around the young celestial body. These grains slowly clump together to form small solid bodies, the first fruits of budding planets, the planetesimals. Under the effect of gravity, these planetesimals reach up to a few kilometres in diameter, eventually forming embryonic planets while clearing the disk of its original dust. The further away their orbits are from the Sun, the more massive they are, as they find more material to agglomerate along their path. From a certain distance from the Sun, the planets are able to attract gases from clouds made of hydrogen and helium until they collapse on themselves, giving rise to the gas giants we know well: Jupiter and Saturn. Uranus and Neptune, being smaller, do not retain gases but only their cores of rock and ice. The planets that form closer to the Sun are called telluric, and are made of rock and metal. They collide violently when their orbits cross to such an extent that only four remain: Mars, Venus, Mercury and Earth. The formation of all these planets takes 100 million years. Theia, a protoplanet, wanders in a stable zone of the cosmos, at the same distance from the Sun as the Earth. When it reaches the size of Mars, Theia is destabilized by the gravitational influence of the other planets. Its orbit becomes chaotic and it collides violently with the young Earth that was forming 4.52 billion years ago. The collision is so violent that Theia's iron core sinks into the heart of the Earth. The rest of the planet and part of the Earth's mantle are expelled into space. All of these materials orbiting the Earth eventually come together to form the satellite that is the Moon, which is about 22,500 kilometres across. The Moon stabilises the Earth's axis of rotation and slows down this movement by means of tidal friction, which explains why at that time a day lasts only 6 hours and a year has 1,434 days. When the Earth began to cool, a solid crust formed, marking the beginning of the Archean Eon about 4 billion years ago. At this time, the first oceans on Earth appeared, created by the condensation of water vapour from volcanic degassing and possibly supplemented by water supplied by comets. These first oceans were the cradle of the first forms of life. Simple single-celled organisms, such as bacteria and archaea, began to develop in the primordial soup, laying the foundations for subsequent biological evolution. In the Proterozoic Eon, which began about 2.5 billion years ago, significant changes occurred in the Earth's atmosphere and biosphere. Oxygen levels began to increase due to the photosynthesis of cyanobacteria, leading to the Great Oxidation Event. This dramatic increase in atmospheric oxygen transformed the terrestrial environment and allowed the evolution of more complex aerobic life forms. During this time, the first eukaryotic cells appeared, which would eventually give rise to multicellular organisms. The Paleozoic Era, which began about 541 million years ago, marked a period of profound diversification of life forms. The Cambrian Explosion, a relatively brief period, saw the rapid appearance of most of the major animal phyla. Marine life flourished with the development of trilobites, brachiopods, and the first fish. In the Ordovician period, life began to colonize the land, with the appearance of the first plants and fungi. ???? As a reminder, videos are posted on SUNDAYS at 6:00 p.m.