The first person to write it down was the Persian astronomer Abd al-Rahman al-Sufi, in 964 CE. He called it a “small cloud” in his Book of Fixed Stars. For nine centuries after that, M31 remained exactly that — a smudge, a curiosity, an unresolved patch of light in the constellation that bears Andromeda’s name.

Everything changed in 1923 when Edwin Hubble identified Cepheid variables in the cloud’s outer regions and measured their distances. The smudge was not inside the Milky Way. It was an entire galaxy — a separate island of stars, far beyond anything astronomers had imagined the universe could contain. The discovery settled the Great Debate between Shapley and Curtis in a single observing run and forced cosmology to scale up by orders of magnitude.

Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen lifted off from Kennedy Space Center at 6:35 p.m. EDT on a machine that had earned a reputation for temperament — the SLS, with its history of hydrogen leaks and slipped schedules. On this evening, it flew clean. The launch window opened and the rocket simply went, which surprised even the crew.

Two days of coasting brought them to the translunar injection burn. After that, Earth shrank in the windows and the Moon grew. On the morning of April 6, Orion crossed the lunar sphere of influence — the invisible boundary where the Moon’s gravity takes over. Koch marked the moment: the spacecraft was now falling toward the Moon rather than climbing away from Earth.