Celsius is a scale and unit of measurement for temperature, named after the Swedish astronomer Anders Celsius who developed a similar scale shortly before his death in 1744.
'Degree Celsius' can refer to a specific temperature on the Celsius scale as well as an interval indicating a difference between two temperatures. Until 1948, Celsius was more commonly known as 'centigrade'.
Until 1954, zero degrees Celsius was defined as the freezing point of water and 100 degrees Celsius was defined as the boiling point of water. These values are still commonly taught in schools to the present day, although in the scientific community there is now a different international agreement that
dictates that the Celsius unit is defined by two different points:
• Absolute zero
The theoretical temperature at which entropy reaches its minimum value. The laws of thermodynamics state that absolute zero cannot be reached
• The triple point of VSMOW (Vienna Standard Mean Ocean Water - specially prepared water)
In modern times, the precise 'triple point' of water is defined as 0.01 degrees Celsius. This is equivalent to 273.16 Kelvin or 32.018 degrees Fahrenheit on other temperature scales.
Normal human body temperature is 36.6 degrees Celsius (310.15 Kelvin or 98.6 degrees Fahrenheit).
The boiling point of water is 99.9839 degrees Celsius precisely (373.1339 Kelvin or 211.971 degrees Fahrenheit).