Sangeetha Pulapaka

Part of the reason gold is so widely found on Earth may be due to its extraterrestrial origins. Gold was present when the Earth was formed, but the original gold sank down into the Earth's core as the planet stabilized, claims BBC News. Scientists are not sure how gold became so common in the Earth's mantle, but research shows meteorites might be responsible, reports Science Daily. This theory claims that a massive meteor bombardment approximately 4 billion years ago brought gold to the upper layers of the Earth.

Some scientists disagree with this theory and think that most gold was already on Earth when the planet formed, according to BBC News. Instead of being pulled down into the Earth's core, it remained in an ocean of magma just below the mantle. Volcanic eruptions then brought it into the mantle.