IRIS Movie of the Day
At least once a week a movie of the Sun taken by NASA's Interface Region Imaging Spectrograph (IRIS) is posted by one of the scientists operating the instrument.
A Different Kind of Movie
Credit: IRIS, LMSAL/NASA, Ted Tarbell
This movie of an active region near the limb (edge) of the Sun is not a conventional motion picture. Instead, it progresses in the wavelength of the light, not time, as the movie plays. It is made from a scan across the active region by the IRIS spectrograph that took about 50 minutes, exposing each column of the movie image one at a time. Each movie frame shows one wavelength across the entire region, in the near ultraviolet (NUV) range of the spectrograph. Since light at different wavelengths arises from different heights and structures in the solar atmosphere, the movie frame in effect moves up and down above the solar surface. Some wavelengths show material high above the surface out beyond the limb of the Sun. Some structures change from bright to dark depending on whether there is extra emission or absorption at neighboring wavelengths. This movie illustrates how IRIS scientists can learn the 3-dimensional structure of the solar atmosphere from careful study of its appearance at different wavelengths.