WE ON Earth are essentially the same distance from the Sun as is the Moon. Both our planet and the Moon receive the same amount of heat, averaged over the year, per square metre of their surface. Yet the Earth’s average surface temperature is 15 °C, while the Moon’s is -18 °C. This difference – a crucial one, as we shall see – is all down to the fact that the Earth has an atmosphere which, rather like a blanket, traps heat that would otherwise escape into space.
The warming of the surface that results is called the greenhouse effect. Often…
