Title:[0562] The visible surface of the Sun Caption:The surface of the Sun, seen in visible light, is called the photosphere. Most of the Sun's radiation is emitted from the photosphere in visible and near-infrared light. Above this layer of opaque gas is the Sun's atmosphere, which is composed of extremely hot gas, is transparent to visible light, and emits radiation primarily in x-ray and ultraviolet wavelengths. This white-light photograph of the Sun taken on 19 February 1982 shows several sunspots including a very unusual spiral sunspot. Copyright:(c) Smithsonian Astrophysical Observatory Credit:Courtesy of National Optical Astronomy Observatories

Title:[1167] The Sun photographed in red hydrogen-alpha light Caption:Full disk photograph of the Sun, taken in red hydrogen-alpha light at the National Solar Observatory, Sacramento Peak, New Mexico. The dark streaks, called filaments, are prominences silhouetted against the bright photosphere. Copyright: Credit:National Optical Astronomy Observatories

Title:[3013] X-rays from active regions on the Sun Caption:Hard and soft X-ray emission from active regions on the Sun, detected from Skylab (1973/4). The X-rays come from "hot spots" overlying cool sunspots in the Sun's photosphere below. Copyright: Credit:NASA/JPL