Tiny Dwarfs, Big Light: Dwarf Galaxies Reionized the Early Universe

New JWST and Hubble observations reveal ultra-faint dwarf galaxies were the primary engines of cosmic reionization, outnumbering large galaxies 100 to 1 and collectively emitting enough ionizing radiation to turn neutral hydrogen into ionized gas, effectively lighting up the early Universe by about a billion years after the Big Bang.