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.
IRIS and SDO co-observing Mercury
Credit: IRIS, LMSAL/NASA, Wei Liu and Bart De Pontieu
IRIS observes only a small part of the Sun at any one time: its field-of-view is much smaller than that of the Atmospheric Imaging Assembly (AIA) instrument onboard the Solar Dynamics Observatory (SDO) which sees the whole solar disk. While Mercury was crossing the solar disk, IRIS was able to track Mercury for chunks of time of about 50 minutes after which IRIS repointed the telescope (which takes about 10 minutes during which no data can be taken). So IRIS was not able to see Mercury during its whole transit. This movie shows a blend of IRIS observations of plasma at 10,000 K with SDO observations of plasma at 100,000 K filling in the gaps when IRIS was repointing. You can tell the IRIS and SDO observations easily apart because IRIS can resolve much smaller details than SDO: the images with larger blocky pixels are from SDO.