The stratopause is the level of the atmosphere which is the boundary between the stratosphere and the mesosphere. In the stratosphere the temperature increases with altitude, and the stratopause is the section where a maximum in the temperature occurs.

This not only occurs on Earth, but on other planets with an atmosphere as well.

On Earth, the stratopause is generally considered to be located at an altitude of 50 km. The atmospheric pressure is around 1/1000th of the pressure at sea level.