Evolution of prominence from 14:06 UT, May 16, 2011 to 00:06 UT, May 18, 2011 in SDO/AIA and Stereo_A-EUVI. Left panels: composite images of 304 Å, 171 Å, and 193 Å wavelengths from SDO/AIA. Right panels: 195 Å wavelength of Stereo_A-EUVI. The white arrows in the top four frames indicate the specific points on images from both spacecraft. F₁ points correspond to the footpoint of tornado-like structure. The brightening is marked with B₁ and B₂ points for identifying areas of interest. Approximate boundaries of prominence are shown by white dotted-curved lines in the lower four panels.