The early universe was filled with a thick fog of neutral hydrogen. Even though the first stars and galaxies emitted copious amounts of ultraviolet light, that light struggled to pierce the fog. It took hundreds of millions of years for the neutral hydrogen to become ionized, electrons stripped from protons, allowing light to travel freely through space.

Astronomers are seeking to understand this unique time of transformation, known as the era of reionization. A newly discovered galaxy illuminated this era in an unexpected way. JADES-GS-z13-1, observed just 330 million years after the big bang, shows bright hydrogen emission that should have been absorbed by the cosmic fog. Theorists are struggling to explain how its light could have pierced the fog at such an early time.