Lasers

Comment on Apollo Moon Landing Hoax – Video Evidence by Matt.

You realise of course that the astronauts who landed on the moon left on the surface a reflector plate. This plate has had lasers fired at it which had then returned to Earth and then been measured showing significant reflectance. Despite the moon having a slightly reflective surface (responsible for the moon being so bright in the night sky), the meters back here on Earth would only show a negligible reading of reflection. The fact that these reading are positive prove there is man-made material on the surface of the moon.
Links:
http://www.physics.ucsd.edu/~tmurphy/apollo/doc/Bender.pdf
http://en.wikipedia.org/wiki/Lunar_Laser_Ranging_experiment