For really accurate measurements check out http://www.physics.ucsd.edu/~tmurphy/apollo/apollo.html http://www.physics.ucsd.edu/~tmurphy/apollo/apollo.html By bo

For really accurate measurements check out http://www.physics.ucsd.edu/~tmurphy/apollo/apollo.html http://www.physics.ucsd.edu/~tmurphy/apollo/apollo.html By bouncing a laser off several reflectors that were left on the moon, they are able to get accuracies of one millimeter.