Celsius Celsius The Celsius scale, also known as the centigrade scale, is a temperature scale used by the International System of Units (SI). As an SI derived unit, it is used by all countries except the United States, the Bahamas, Belize, the Cayman Islands and Liberia. It is named after the Swedish astronomer Anders Celsius (1701–1744), who developed a similar temperature scale. The degree Celsius (°C) can refer to a specific temperature on the Celsius scale or a unit to indicate a difference between two temperatures or an uncertainty. Before being renamed to honor Anders Celsius in 1948, the unit was
Temperature measurement also to confounding with atmospheric pressure changes. These early devices were called thermoscopes. The first sealed thermometer was constructed in 1641 by the Grand Duke of Toscani, Ferdinand II. The development of today's thermometers and temperature scales began in the early 18th century, when Gabriel Fahrenheit produced a mercury thermometer and scale, both developed by Ole Christensen Rømer. Fahrenheit's scale is still in use, alongside the Celsius and Kelvin scales. Many methods have been developed for measuring temperature. Most of these rely on measuring some physical property of a working material that varies with temperature. One of the most common