This video takes a relaxed look at a tense process — cleaning and recoating the surface of one of the ESO Very Large Telescope’s 8.2-metre main mirrors.
Every night the huge mirrors are exposed to the atmosphere whilst uncovered during observing sessions. They gradually accumulate dust and other pollutants that reduce their reflectivity, making them less effective at capturing faint light from the cosmos. So they are regularly removed from the telescope, taken down the mountain to the recoating facility, cleaned and finally recoated with a thin and highly reflective new aluminium layer.
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