Cosmic kilonovae forge Earth's gold, GW170817 confirms
The 2017 GW170817 neutron‑star collision proved that heavy elements like gold are produced by rapid neutron‑capture (r‑process) in such mergers, ejecting about 6% of a solar mass of material (roughly 20,000 Earth masses) including ~200 Earth masses of gold and ~500 Earth masses of platinum. This material was dispersed through the galaxy before the Solar System formed, explaining why Earth’s gold traces back to ancient stellar explosions. While neutron‑star mergers clearly produce gold, newer analyses suggest they may not account for all galactic heavy elements, with other sources potentially contributing.