This is the universal Photosphere temperature constant

Planck temperature is a fundamental physics constant

The standard temperature used in the Standard Temperature and Pressure (STP) often used to define Sp

The Reduced Temperature calculator computes the reduced temperature, one of a set of reduced properties of a fluid substance, defined by the ratio of the actual temperature (T) to the substance's critical temperature (T_{c}).

Planck Temperature, `T_P` is the unit of temperature in the system of natural units known as Planck units. It serves as the defining unit of the Planck temperature scale. In this scale the magnitude of the Planck temperature (denoted `T_P`) is equal to 1, while that of absolute zero is 0. Other temperatures can be converted to Planck temperature units. This constant returns the Planck temperature in degrees Kelvin by default.

The STP (temperature) is 273.15 degrees Kelvin (0 °C, 32°F). The equivalent values of Standard Temperature are also:

The average temperature of the Universe as a whole is measured from astronomical observations taking measurements of background microwave radiation, and from numerous other techniques.