ASTA01H3 Lecture Notes - Lecture 11: Exoplanet, Zircon, Zodiacal Light
Document Summary
Chapter 12: the origin of the solar system. The history of the atoms in your body. By the time the universe was three minutes old, the protons, neutrons, and electrons now in your body had come into existence. Although those particles formed quickly, they were not linked together to form the atoms that are common today. Most of the matter was hydrogen (almost 75%), and about 25% was helium. Very few (<1%) of the heavier atoms were made in the big bang. The big bang also formed the so-called dark matter, which permeates the planetary systems at very low density, but has very little interaction with them. During the rst few hundred million years after the big bang, matter collected to form galaxies containing billions of stars. Our galaxy was built ~8. 8 gyr ago (so-called thin disk) Nuclear reactions inside stars combine low-mass atoms, such as hydrogen, to make heavier atoms.
