Credit: NASA/SDO and the AIA, EVE, and HMI science teams
The Sun in ultraviolet (UV) "light" on September 19, 2010. This image was captured by the Atmospheric Imaging Assembly (AIA) instrument on NASA's Solar Dynamics Observatory (SDO) spacecraft. This image shows high energy UV radiation with a wavelength of 30.4 nanometers (304 angstroms). UV radiation of this wavelength is emitted by helium atoms in the chromosphere, the lower portion of the Sun's atmosphere, at a temperature around 50,000 kelvins (about 50,000° C or 90,000° F).