Astronomers use different colors of light and other energy to see different "parts" of the Sun. The different energies come from places on the Sun with different temperatures. White light shows the photosphere, the visible "surface" of the Sun. Infrared "light" from helium, red light from hydrogen, and ultraviolet (UV) "light" from calcium help us see features in the chromosphere. The chromosphere is the Sun's lower atmosphere, where temperatures rise to tens of thousands of kelvins. The Sun's upper atmosphere, called the corona, is really hot with temperatures over a million kelvins. We can see the corona with X-rays and ultraviolet radiation.
Original artwork by Windows to the Universe staff (Randy Russell) using images courtesy of SOHO (NASA and ESA), NCAR/HAO/MLSO, Big Bear Solar Observatory, and SDO/AIA.