Earth was formed about 4.5 billion years ago.
During its existence it has passed through many stages of development, has evolved from a glowing ball in the only known to mankind planet inhabited by living organisms.
The emergence of land directly related to thethe formation of the solar system. Of course, all theories about the earth's appearance are only hypotheses, which are constantly reviewed based on the new data. Currently considered the main hypothesis about the formation of planets in the solar system, including Earth, clouds of gas and dust orbiting the sun.
About 4.6 billion years ago, thanks togravitational collapse of a cloud of interstellar dust of the sun appeared, which became the center of a new planetary system. Around the Sun formed a disk of material gas and dust clouds. This CD is a high speed revolved around the sun, has particles in it constantly interacted and connected repelled, created the seal in the disk, so that it gradually broke up into separate parts, the so-called planetesimals.
The largest planetesimals beganattract other clumps of matter and compacted under the influence of gravitational forces. The solar system during its formation had a form different from the present, it included about 100 protoplanets, but the system was much smaller than it is now. Proto-planet faced, forming the planets known to us today, including the Earth, at the same time formed the planets and satellites such as the Moon.
Originally, Earth had a very largetemperature, ie a substance on it is in the molten state and violently stirred, more dense metals fell down, forming a metallic core, silicate rose up, forming a mantle. The metal core made possible the appearance of the magnetic field of the planet.
Gradually the planet cooled, reducedVolcanic activity in the atmosphere accumulated large amounts of water. Cooling of the planet has led to the formation of the Earth's crust. About 3.8 billion years ago on Earth were the first living organisms formed the biosphere, which fundamentally influenced the further development of the planet.