This air in this tube is being subjected to a high-voltage electric field, which frees some of the electrons that would normally cling tightly to the N2, O2, and other atmospheric gases inside, creating a plasma. The staff at the Exploratorium, a science museum in San Francisco, have set this one up with a magnet to perturb the electric field and a switch-operated vent hole to tweak the airflow, allowing visitors to manipulate the light show.
Credit: Craig Bettenhausen/C&EN
Do science. Take pictures. Win money. Enter our photo contest here.