It is measured on a scale. One widely used scale is the Celsius scale. Ice, for example, measures 0°C on the Celsius scale, while water in a flower vase in a room may be twenty degrees hotter (20°C) and a boiling kettle would be a hundred degrees hotter (100°C) The surface of the Sun is six thousand times hotter than ice (6,000°C), and inside the Sun it is fifteen million times hotter than ice (15,000,000°C).