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.
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26 Oct 2017
Commotion in Solar Eruption Motion
Credit: IRIS, LMSAL/NASA, SAO, Jakub Prchlik
IRIS simultaneously observes both solar images and spectra. The simultaneous observations reveal the solar atmosphere's 3D motions. During the above observation with a picture of Earth from DSCOVR/EPIC for scale, IRIS observed a moderate intensity C5.4 class flare. The flare creates two bright ribbons on the solar surface and ejects some material. The ejected material starts as a wispy brightness originating from bottom flare ribbon. Then the eruptive material moves to the image's bottom left. However, observers would not know the motion with respect to the solar surface without spectra (the four panels with bright lines left of the image). The spectra show wispy blue-shifted (i.e. left of the bright spectral lines) emission during the eruption. Blue-shifted emission indicates the material initially moved towards IRIS, thus away from the sun. However, the material did not leave the sun. Instead, you see red-shifted emission (i.e. motion towards the sun) when the wispy material returns at the observation's end. Therefore, combining images and spectra helps scientists understand the commotion in solar eruptions.