Shadow bands are an oscillatory light phenomenon found during a solar eclipse. They appear as lines of shadows that move across the ground just prior to and following eclipse totality. They have been observed for centuries  and appear for approximately 120 seconds prior to and immediately after eclipse totality.

The accepted atmospheric scintillation hypothesis proposes that the Earth’s atmosphere produces this effect by refracting the highly focused light from the eclipse corona. Effectively, the focused light of the solar crescent is being smeared by the atmosphere. Patterns start out random and disorganized but become more organized as the crescent narrows towards totality. Band direction and speed would be determined by variables of the atmosphere, including wind speed and direction.


Since atmospheric variables (pressure, density, wind speed & direction) change with altitude, we expect in-situ shadow band measurements to vary throughout the atmosphere. To directly characterize shadow bands during a solar eclipse, we propose a high altitude balloon mission carrying instruments for measuring shadow band size and frequency, along with atmospheric conditions.