A video of the Aug 21, 2017 lunar transit as viewed by the Solar Dynamics Observatory (SDO.) The Sun appears in visible light, and 171 angstrom extreme ultraviolet light. The movie shows the Sun moving a bit because SDO has a hard time keeping the Sun centered in the image during a transit, because the Moon blocks so much light. The fine guidance systems on the SDO instruments need to see the whole Sun in order keep the images centered from exposure to exposure. Once the transit was over, the fine guidance systems started back up, once again providing steady images of the Sun.
NASA/SDO; Goddard Space Flight Center
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