Optical observations of the AMPTE artificial comet from the Northern Hemisphere

The AMPTE artificial comet of Dec. 27, 1984, developed a well-defined core (maximum size about 160 x 100 km) of cold barium ions, surrounded by a diffuse coma, 500 km in diameter, consisting of ions extracted from the core. A plasma tail extended from the core, mainly directed away from the sun. The plasma tail and diffuse coma consisted of energetic ions (above 200 eV). Confounding predictions, the artificial comet survived for barely five minutes, and the core of the comet moved southward, rather than in the direction of the solar wind.