Researchers report the detection of erythrulose, a four-carbon sugar, in a gas-and-dust cloud called G+0.693−0.027 near the Milky Way’s center. Using ultrasensitive radio-telescope observations, they matched multiple spectral lines to laboratory data. The sugar appears at least eight times more abundant than similar three-carbon sugars, which were not detected. Astrochemical models suggest it can form on interstellar dust from simpler two-carbon molecules. The findings may broaden ideas about how life’s ingredients spread through space.