Why are hydrogen, helium and lithium important and how did these elements come to be on Earth?

1 Answer
Mar 13, 2016

The elements are fundamental building blocks of the "normal matter" in the universe.


Hydrogen, helium and lithium were forged 13.8 billion years ago about 500,000 years after the universe came into existence. But even before this, the fundamental forces and particles were also forged. These elements eventually condensed into galaxies and then into stars. When stars started nuclear fusion, more helium was produced.

Some 1st generation stars reached the end of their lives about 7 billion years ago and expanded into Red Giants. During this phase, nucleosynthesis forged many of the next series of elements up to about iron. Some stars exploded into Supernovas and all the remaining elements were forged under these enormous temperatures and pressures. The elements drifted around in space and gradually formed nebulae, which became the nurseries for new stars - like our own.

The gases elements hydrogen and helium collapsed to form the sun, while most of the other heavier elements coalesced in the inner rocky planets, including Earth.

http://palaeos.com/cosmos/cosmology.html image source here