Neil deGrasse Tyson explains that the atoms in your body came from massive stars that exploded as supernovae, scattering carbon, nitrogen, and oxygen across the galaxy. Those elements coalesced into planets and became you. We are made of stardust.
Chapters
The most astounding fact is the knowledge that the atoms that comprise life on Earth, the atoms that make up the human body, are traceable to the crucibles that cooked light elements into heavy elements in their core under extreme temperatures and pressures. These stars went unstable in their later years. They collapsed and then exploded, scattering their enriched guts across the galaxy. Guts made of carbon, nitrogen, oxygen, and all the fundamental ingredients of life itself. These ingredients become part of gas clouds that condense, collapse, form the next generation of solar systems, stars with orbiting planets. And those planets now have the ingredients for life. So that when I look up at the night sky, And I know that, yes, we are part of this universe, we are in this universe, but perhaps more important than both of those facts is that the universe is in us.