Milky Way Edge Revealed: Outer Disk Extends About 40,000 Light-Years

Researchers analyzing data from APOGEE-DR17, Gaia, and LAMOST-DR3 identify the Milky Way’s edge at roughly 40,000 light-years from the center, marking the final star-formation site beyond which only older stars remain. The outer disk shows a U-shaped stellar-age profile and breaks in the light profile, explained by star migration and bar-driven dynamics, while diffuse outer gas suggests little current star birth.