The kelvin is a unit of measure for temperature based upon an absolute scale. It is one of the seven base units in the International System of Units (SI) and is assigned the unit symbol K.
The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all thermal motion ceases in the classical description of thermodynamics.
The Kelvin scale is named after the Belfast-born, Glasgow University engineer and physicist William Lord Kelvin (1824-1907).
Unlike the degree Fahrenheit and degree Celsius, the kelvin is not referred to or typeset as a degree. Subtracting 273.16 K from the temperature of the triple point of water (0.01 °C) makes absolute zero (0 K) equivalent to -273.15 °C (-459.67 °F).
In astronomy, the stellar classification of stars and their place on the Hertzsprung-Russell diagram are based, in part, upon their surface temperature, known as effective temperature. The photosphere of the Sun, for instance, has an effective temperature of 5,778 K.