Solar images in three different wavelengths in extreme ultraviolet light are combined together to show solar activity over almost three months (June 2 – Aug. 26, 2010). Each wavelength is shown in a different color. The wavelengths are at 211 (red – 2 million degrees), 193 (green – 1.3 million degrees), and 171 Angstroms (blue – 600,000 degrees). The cadence is basically a frame every 45 minutes. The brightest areas are active regions, which have stronger magnetic field than the surrounding area.

credit: NASA

source: http://sdo.gsfc.nasa.gov/gallery/potw.php?v=item&id=22