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1 CE
Planetary Accretion
//4.6 billion years ago// Accretion is defined as the: formation of planets and other bodies by the collection of material through gravity. The solar system began as a rotating cloud of stardust. Most of the mass became concentrated in the middle, forming the sun. Smaller concentrations of mass rotating around the centre formed the planets, including Earth. Earth gradually acquired more mass through this process. -
2
Core Formation
// 4.4 billion years ago // There was a lot of heat which caused everything to melt and form oceans of magma. Since Earth was liquid, the denser substances moved to the centre, while the less dense ones moved to the surface. The process of planetary differentiation is what got Earth its layers. The Earth was in a hazy, steamy atmosphere. -
3
Formation of the Moon
// 4.51 billion years ago // There are three theories as to how our planet's satellite could have been created: the giant impact hypothesis, the co-formation theory and the capture theory. The most well-known, the giant impact hypothesis suggests that the moon formed when an object smashed into early Earth. This happened 20 to 100 million years after Earth had formed. -
4
Planetary Cooling
// By 4 billion years ago // the earth had cooled enough for the outer layers to have solidified and for oceans to form. The earth cooled from the outside in, and the still molten core is the remnants. "That heat is also what keeps the earth geologically active, and without it, nothing that we know of the earth would exist today, no continents, no volcanos, no mountains, no oceans, and almost certainly no life." -
5
End of Heavy Bombardment
//4.1 to 3.8 billion years ago//
One theory holds that a gravitational surge caused by the orbital interaction of Jupiter and Saturn sent Neptune careening into the ring of comets in the outer Solar System. The disrupted comets were sent in all directions and collided with the planets. Comets are predominantly composed of water and so when the heavy Bombardment slowed down, the first sign of water was created on Earth.
