Astronomy Picture of the Day . ... From top to bottom, these stacked panels show the largest sunspot group in a decade in visible, extreme ultraviolet, and x-ray light. All were taken on March 29, around the time the famous solar active region, cataloged as AR 9393 , was at its peak size -- over 10 times the size of planet Earth. The panels illustrate how the "appearance" of the active region changes, when imaged in electromagnetic radiation (light) of progressively shorter wavelengths. ...