ABSOLUTE ZERO, or zero degrees absolute, is the lowest temperature on the Kelvin thermometric scale (absolute thermodynamic scale of temperature).
It is the temperature matter would have if ali of the heat were removed from it. Therefore, absolute zero is the lowest temperature possible.
The planets far from the sun are so remote from any heat source that their temperatures are thought to be near zero degrees absolute. Earth is much warmer. To cool an object to temperatures near absolute zero on this planet, it must be subjected to a fairly complicated refrigeration process. A temperature of zero degrees absolute can never be realized, but only approached. A few millionths of a degree above absolute zero is the lowest temperature ever attained in the laboratory.
The thermal energy of matter is viewed as the rapid random motion of its molecules, and this energy is proportional to temperature. As the temperature of an object is reduced, therefore, the disordered motions of its molecules become less agitated. In the classical view of nature, molecular motion ceases altogether at absolute zero.
With the advent of quantum mechanics, this classical view required modification. Matter is now thought to retain a zero-point energy of random molecular motion at absolute zero.