Distance to the Moon
The Moon is now, on average, 384,467km (238,897 miles) away from Earth. It revolves around Earth on an elliptical or oval shaped orbit, so sometimes it is nearer to the Earth and sometimes farther away. We know the distance to the Moon exactly because special reflectors were left on the Moon’s surface by the astronauts of the Apollo missions. Astronomers bounce laser beams off these reflectors and, because they know the speed at which the light of these laser beams travels, they can calculate the distance by the length of time it takes for the beam to get to the Moon and back.
The Moon is slowly moving away from Earth at a rate of 3.78cm (1.5 inches) per year. If the Moon moved far enough away this would have a catastrophic effect on the Earth’s climate. However, the Moon is moving so slowly that it would be billions of years before this happened.