Earth is thought to have formed about 4.6 billion years ago.
Earth was formed in a rotating disk of particles and grains that had condensed around a central protosun.
The condensed rock, iron, and mineral grains were pulled together by gravity, growing to a planet-sized mass.
Bits and pieces of matter not incorporated into planets bombarded the planets and their moons.
This bombardment was so intense that the heat generated by impact increased the surface temperature to the melting point.
The heat was sufficient to melt the entire surface of the Earth to a layer of molten lava. The lava eventually cooled and crystallized to solid igneous rocks.
Earth was formed in a rotating disk of particles and grains that had condensed around a central protosun.
The condensed rock, iron, and mineral grains were pulled together by gravity, growing to a planet-sized mass.
Bits and pieces of matter not incorporated into planets bombarded the planets and their moons.
This bombardment was so intense that the heat generated by impact increased the surface temperature to the melting point.
The heat was sufficient to melt the entire surface of the Earth to a layer of molten lava. The lava eventually cooled and crystallized to solid igneous rocks.
The earth's second melting
The interior slowly accumulated heat from the radioactive decay of uranium, thorium, and other radioactive isotopes.
After about 100 million years of accumulating heat, parts of the interior became hot enough to melt to pockets of magma.
Iron and other metals were pulled from the magma toward the center of the Earth, leaving dense rocks on the surface.
With each cyclic melting, the heavier abundant elements were pulled by gravity toward the center of the Earth.
After about 100 million years of accumulating heat, parts of the interior became hot enough to melt to pockets of magma.
Iron and other metals were pulled from the magma toward the center of the Earth, leaving dense rocks on the surface.
With each cyclic melting, the heavier abundant elements were pulled by gravity toward the center of the Earth.