After the Sun formed about 4.6 billion years ago from the collapse of a massive cloud of dust and gas called the solar nebula, the remaining material in the surrounding protoplanetary disk began to coalesce into planets, including Earth
. Here is how Earth formed after the Sun:
- The solar nebula, a rotating disk of gas and dust left over from the Sun's formation, contained particles of rock, metal, and ice.
- These particles collided and stuck together through a process called accretion, forming larger clumps called planetesimals.
- Planetesimals continued to collide and merge, growing into Mars-sized protoplanets.
- Earth formed as one of these protoplanets by accumulating more material over about 10 to 20 million years, possibly as quickly as 3 million years according to recent studies
- During this time, Earth grew larger through countless collisions with dust, asteroids, and other protoplanets.
- One major collision with a Mars-sized body (Theia) is believed to have created debris that eventually formed the Moon
- As Earth grew, it heated up due to radioactive decay, gravitational compression, and impacts, causing differentiation: heavier elements like iron sank to form the core, while lighter materials formed the crust
- The early Earth was bombarded by asteroids and comets, which contributed to its heat and delivered water that helped form oceans
- Over time, volcanic activity and tectonics shaped Earth's surface, leading to the formation of continents and atmosphere.
In summary, Earth formed by gradual accumulation of dust and debris orbiting the young Sun, followed by heating and differentiation, and was shaped by collisions and impacts in the early solar system
