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.
Mercury Ingress
Credit: IRIS, LMSAL/NASA, Bart De Pontieu
IRIS observed the transit of Mercury across the solar disk. This movie shows the initial contact of Mercury and the solar disk. The panel on the right shows emission from plasma at 80,000 K. Mercury does not emit in the wavelengths IRIS observes so appears as a dark feature crossing the disk. The two panels on the left show spectra of the part of the Sun covered by our slit (dark vertical line in the right panel). Observations such as these are not only pretty but also useful for calibration of the instrument, in particular how sharp our images are.