The changes of a coronal cell region as solar rotation carries it across the solar disk as seen with NASA's STEREO-B spacecraft. The camera is fixed on the region (panning with it) and shows the plumes changing to cells and back to plumes again -- based on the observatory's perspective -- during the interval June 7-14, 2011.
One day in autumn, 2011, Neil Sheeley, a solar scientist at the Naval Research Laboratory in Washington, D.C., did what he always does - look through the daily images of the sun from NASA's Solar Dynamics Observatory (SDO). But on this day he saw something he'd never noticed before: a pattern of cells with bright centers and dark boundaries occurring in the sun's atmosphere, the corona. When the cells were discovered in the fall of 2011, the SDO and the two STEREO (short for Solar Terrestrial Relations Observatory) spacecraft each had widely different views of the sun. Thus, as the 27-day solar rotation carried the coronal cells across the face of the sun, they appeared first in STEREO-B data, then in SDO, and finally in STEREO-A, before starting over again in STEREO-B. In addition, when one observatory looked down directly on the cells, another observatory could see them from the side. The researchers used time-lapse sequences obtained from the three satellites to track these cells around the sun. When an observatory looked down on one of these areas, it showed the cell pattern that Sheeley first noticed. But when the same region was viewed obliquely, it showed plumes leaning off to one side. Taken together, these two-dimensional images reveal the three-dimensional nature of the cells as columns of solar material extending upward through the sun's atmosphere, like giant pillars of gas.
