Nucleosynthesis

Nucleosynthesis is the process of creating new atomic nuclei from pre-existing nucleons (protons and neutrons). The first nuclei were formed about three minutes after the Big Bang, through the process called Big Bang nucleosynthesis, which formed the hydrogen and helium content of the first stars, and is responsible for the general hydrogen/helium ratio of the universe today. In space, cosmic ray spallation is also a significant source of specific nuclei (9Be and 10,11B) that are not created by stellar nucleosynthesis.