10 Most Important Events In Earth's History

Number 1: The Solar System Formation. This happened 4.6 billion years ago. The most common theory about the formation of the Solar System is the Solar Nebula. When the nebula collapsed, it rotated faster and flattened into a disk pulling in most matter around the center to form our sun. Solar winds pulled away lighter elements such as hydrogen and helium which formed our gas giants.

Number 2: The Formation of our Moon. This happened 4.5 billion years ago. The moon is the biggest satellite in our solar system. There are many theories about how the moon formed but the most accepted theory is Theia, a planet the size of Mars which smashed into Earth. This event nearly destroyed Earth. This ejected huge amounts of dust. The dust began to harden which became our moon.

Number 3: The first seas, land, and atmosphere. This happened 4.4 to 3 billion years ago. The first tectonic plates formed and the first continents formed at the surface along with volcanoes which densified the first atmosphere composed of solar nebula and greenhouse gases. When the atmosphere became thick enough the first bacteria formed and began producing oxygen about 2.8 billion years ago.

Number 4: Origins of life. This happened 3.8 billion years ago. High concentrations of organic compounds present on Earth began to combine and synthesize into larger molecules forming the first proto-cells.

Number 5: The Great Oxygenation Event. This happened 3.2 to 2 billion years ago. Archean Stromatolites are the oldest of oxygen-producing organisms. they used fermentation to break down complex material into simple compounds.

Number 6: The Snowball Earth and the emergence of Eukaryotes. This happened 2.2 billion years to 900 million years ago. A thick layer of ice covered the planet from the poles to the equator. After this event primitive life forms such as Eukaryotes and bacteria continued to evolve and adapt to the environment surrounding them. They later became multicellular plants around 1 billion years ago and the first animals soon after.

Number 7: The Cambrian Explosion and Pangea. This happened 542 to 180 million years ago. In the fossil record it shows that a sudden emergence of complex organisms formed during the Cambrian period. On the other hand the surface was facing much tectonic activity that continued dispersing and aggregating the continental plates into a supercontinent called Pangea.

Number 8: Colonization of the land and the evolution of Tetrapods. This happened 530 to 310 million years ago. the amount of oxygen released in the air created the Ozone layer which made ultraviolet light less ready so that organisms can flourish on land. Plants and fungi were the first to colonize the land and later were the arthropods. Lobe-finned fish were the first vertebrates to venture onto land and later evolved to the first amphibians.

Number 9: The Mezozoic Era and the rise of Mammals. This happened 251 to 30 million years ago. After the permian extinction a new group of animals evolved from the reptiles. They were the dinosaurs. The dinosaurs took over the trine of the reptiles for about 160 million years until the KT event happened leaving the mammals to take their throne. The mammals soon spreader out across the entire earth and soon took to the oceans taking the place of the Mosasaurus.

Number 10: Human Evolution and Civilization. This happened 25 Million years ago until now. A group of mammal evolved to the primates about 25 million years ago which one species would change the entire earth forever. The reason to how these primates evolved differently is unclear. The first primates lived in Africa and soon moved away to other parts of the globe. After the discovery of fire they initiated tribes, culture, practices, and language. In less then a million years humans were able to build complex societies and advanced technology allowing them to venture to space.

Written By: Dinoboy102

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