In 1933, Fritz Zwicky discovered that galaxies were moving as if they contained far more mass than we could see, a mystery later confirmed by Vera Rubin when she showed galaxies should spin apart if only visible stars were holding them together. This invisible mass became known as dark matter. In this episode, Wyatt, Pascal, and HattieRose explore how math and redshift revealed this hidden structure of the universe and how the Nancy Grace Roman Space Telescope will help map its influence across the cosmos.