An artificial aurora was generated during a trimethyl aluminum (TMA) release from the October 2000 TOMEX rocket launch. Cameras in several locations filmed the optical emissions, believed to be associated with small amounts of kerosene added to the TMA liquid. The geometry of the launch trajectory with respect to the magnetic field and camera viewing angles has provided new insight on the source of the emissions. Surprisingly, the aurora appears to be associated with the vertical footprint of the rocket, rather than the magnetic footprint of the rocket, as previously assumed. The new observations favor a generation mechanism involving large particles >1 ¿m falling to 90 km altitude.