sentences:  The concentration of photons at a specific time appears when the laser is aimed at the Apollos 11, 14 or 15 landing sites; otherwise the expected featureless distribution is observed.The Apollo reflectors are still in use.Strictly speaking, although retroreflectors left by Apollo astronauts are strong evidence that human-manufactured artifacts currently exist on the Moon and that human visitors left them there, they are not, on their own, "conclusive" evidence.