It’s Hydrogen that’s existed since the universe cooled enough for electrons and protons to make atoms. Seconds after the big bang.
That’s most hydrogen.
It’s never been fused into heavier elements just still sticking around and caught in the planetary part of the solar system rather than the sun itself. Or any previous suns.
There’s some helium like that but most helium was formed inside suns later, and heavier elements all formed later in suns or supernovas.
It’s Hydrogen that’s existed since the universe cooled enough for electrons and protons to make atoms. Seconds after the big bang.
Atoms didn’t exist until 380,000 years after the big bang. Before that the universe was too dense for atoms to form and everything existed as a hot dense plasma where no electron could be captured by protons and neutrons. The protons that make up the nucleus of hydrogen did exist, it’s just that everything was too energetic to become an atom yet.
When fusion or fission occurs you get new atoms.
It’s Hydrogen that’s existed since the universe cooled enough for electrons and protons to make atoms. Seconds after the big bang.
That’s most hydrogen.
It’s never been fused into heavier elements just still sticking around and caught in the planetary part of the solar system rather than the sun itself. Or any previous suns.
There’s some helium like that but most helium was formed inside suns later, and heavier elements all formed later in suns or supernovas.
Atoms didn’t exist until 380,000 years after the big bang. Before that the universe was too dense for atoms to form and everything existed as a hot dense plasma where no electron could be captured by protons and neutrons. The protons that make up the nucleus of hydrogen did exist, it’s just that everything was too energetic to become an atom yet.