Formation of our Solar System & Hadean Time (4560-3800Ma)
1
Big Bang:
About 15 billion years ago, all energy in the universe was contained at an infinitely small point of singularity with extreme temperature, pressure and density. Then a tremendous explosion started the expansion of the universe. Today the galaxies are still traveling away from each other at great speeds.
2
Contraction of Nebulae:
After about 300,000 years, matter began to condense from enegy forming particles and later, atoms of hydrogen, helium and heavier elements. Subsequently, nebulae gradually condensed out of huge clouds of gas and dust.
3
Formation of Galaxies:
About 2 billion years after the Big Bang, matter in the nebulae began to coalesce to form galaxies.
4
Generation of Protoplanets:
About 4.6 billion years ago, our sun was born in the Milky Way Galaxy. As mass collapsed under gravity towards the sun, the solar disk rotated. Most matter was swept to the centre where it was hot enough for fusion reactions. Dust particles accreted to form protoplanets which revolved around the sun to give birth to our Solar System.
5
Evolution of homogenous asteroids:
Heat from impacts and radioactive decay warmed the interiors of the protoplanets. On smaller planetary bodies the heat escaped quickly and they remained fairly homogeneous. These became the source for the chondritic meteorites that fall onto the Earth's surface today.
6
Differentiation of Planets:
On larger protoplanets, the heat was not lost quickly enough, and they began to melt. Dense molten heavy metals pooled together and sank towards their centre to form corez. Lighter silica luquid or molten lava rises to the surface leaving denser solid minerals in the mantle. The result was a differentiation of these protoplanets into planets with a metallic core, and rocky mantle and crust.
