Absolute zero is 2.725 K lower than the temperature of the cosmic microwave background. Selected basis: approximate values.
Logarithmic view is unavailable for zero or negative measurements. Linear values remain available.
Celsius and Fahrenheit zero points are offsets. Compare temperature differences, not ratios in °C or °F. The kelvin axis starts at absolute zero.
0 K - Temperature; approximate.
Absolute zero is the lowest temperature permitted by thermodynamics, where a system has the least thermal energy available to it.
The zero of the thermodynamic kelvin scale. It is approached in experiments, not reached by ordinary finite cooling.
NIST — 2022 CODATA fundamental constants2.725 K - Temperature; approximate.
The cosmic microwave background is faint thermal radiation filling the universe, left over from the early stages after the Big Bang.
The temperature of the nearly blackbody relic radiation. It is not the temperature of every object in space.
NASA — COBE science results
There’s always another scale
TemperatureAbsolute zero0 KAbsolute zero is the lowest temperature permitted by thermodynamics, where a system has the least thermal energy available to it.
TemperatureCosmic microwave background2.725 KThe cosmic microwave background is faint thermal radiation filling the universe, left over from the early stages after the Big Bang.TemperatureRoom temperature20 °CRoom temperature describes indoor air conditions generally considered comfortable for people and suitable for ordinary activities.
SpaceSun1,391,000 kmThe Sun is the star at the centre of the Solar System.
Fundamental physicsPlanck temperature1.417 × 10³² KThe Planck temperature is a theoretical temperature scale at which quantum gravitational effects are expected to become important.Side by side
Illustrative artwork · not to scale
Illustrative artwork · not to scale
Illustrative artwork · not to scale
Illustrative artwork · not to scaleGot a good eye for scale?