The universe is nearly 14 billion years old. About a second after the Big Bang, the universe was filled with protons, neutrons and electrons, all swimming in a “sea” of particles of light known as photons. This energetic radiation initially prevented the formation of hydrogen atoms (made of one proton and one electron) and heavier atomic nuclei (with multiple protons and neutrons). It was only after a few minutes that the atomic nuclei of the two lighter elements helium (two protons) and lithium (three protons) formed.
To this day, hydrogen and helium make up the majority of the matter present in the universe. Yet without all the many different types of atoms listed in the periodic table of elements, neither planets nor human life would exist. Stars were actually responsible for producing most of the elements. Inside a star, hydrogen atoms fuse to form helium. In stars that have more mass, this process of nuclear fusion also creates carbon, oxygen and heavier elements up to iron. Elements heavier than iron are formed when atoms acquire even more protons and neutrons. However, this requires physical conditions that only occur in supernova explosions and red giant stars. We are indeed all made of stardust!
Once all these elements had “hatched”, supernovae and stellar winds scattered them as stardust in space. Later on, when new galaxies formed out of gas, the heavy elements that now existed could also form planets. After that (on planet Earth, at least), life evolved. Our solar system materialised about 4.6 billion years ago. Earth is the same age.
This question was answered by Henning Krause of the Communications and Media Relations department at the Helmholtz Association.