TES traced the abrupt disappearance of the seasonal polar caps. In the south, for example, as the Sun rises in local spring, most of the seasonal polar cap remains near the temperature of carbon-dioxide frost, which is about 150 kelvins (-123° Celsius or -189° Fahrenheit). Then over about 20 days, its temperature climbs rapidly as the frost becomes patchy and disappears. NASA/JPL/Arizona State University