Revise GCSE Physics

Question:How thick is the atmosphere?

The Atmosphere does not have a fixed cut off point, because the atmosphere gets thinner and thinner as the altitude is increased.

The internationally agreed boundary between the atmosphere and outerspace is called the The Karman line, which is at an altitude 100 kilometres.

There are still air particles beyond this line, and so still some atmosphere, and therefore different sources give other altitudes for the edge of the atmosphere.