At 1:37 a.m. local time (00:37 Universal Time) on February 23, 2021, the Visible Infrared Imaging Radiometer Suite (VIIRS) on the NOAA-20 satellite captured this image of Mount Etna—a highly active volcano on the Italian island of Sicily. The nighttime image shows a volcanic plume that has been partially illuminated by the glow of the eruption spreading west across Sicily. The image was acquired by the VIIRS “day-night band,” which detects light in a range of wavelengths and uses filtering techniques to observe signals such as molten lava, city lights, and reflected moonlight. NASA Earth Observatory image by Joshua Stevens, using VIIRS day-night band data from the Joint Polar Satellite System.
