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A star that existed before the solar system exploded due to the dissymmetry between the gravity of star and the inner pressure. Through the supernova, a previous star released a nebula, which initiated the formation of the solar system.
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Def: Accumulation of particles(rock and dust) into a formation of the planets and a star by gravitationally attracting more matter.
Event: Approximately 4.6 billion years ago, the solar system was a cloud of dust and gas known as a solar nebula. Through the planetary acceleration, gravity pulled the material in on itself as it began to spin, forming the sun in the center of the nebula. -
Giant-impact hypothesis: the Moon formed out of the rocks left over from a collision between Earth and Theia, an astronomical body the size of Mars, approximately 4.5 billion years ago
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The earth cooled down over time. This event formed a solid crust and allowed liquid water on the surface. Planetary cooling of earth began with the formation of the planet and ended 4.0 billion years ago.
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The Earth formed from a cloud of dust and gas, and material began to come together to form kilometer-sized planets known as “planetesimals”, with a core made up with a combination (called an alloy) of iron and nickel, along with small amounts of other dense elements like gold, platinum, and uranium.
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It was when a mammoth amount of asteroids impacted the terrestrial planets. Earth was one of them. This is what completed the accretion of the planets. It also gave the source of water to the earth.
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single-celled micro-organisms or cell membrane known as prokaryotes seems to have first appeared on earth.
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Earth's solid iron core formed a billion years ago and is still growing: Innermost part of our planet was created when it 'froze' Earth's solid iron inner core formed between one billion and 1.5 billion years ago.
