The Moon rang for about an hour after a strike

Apollo seismometers recorded the shock of impacts reverberating in the lunar crust for tens of minutes, sometimes about an hour. The Moon is dry, and dry rock does not damp a wave the way Earth does.

The Apollo missions left seismometers. When a spent lunar module, or a discarded stage, was sent into the surface on purpose, the signal that arrived was not a thud and a silence. It built, and it stayed, a coda of scattered waves lasting far longer than the same mass of explosive would ring on Earth. The reports from the early landings describe reverberation on the order of an hour. The crust is fractured, so waves bounce, and it is vanishingly dry, so they are not soaked up. A bell is the metaphor everyone reached for. A bell is the wrong instrument. The right picture is a damper missing.

Moonquakes, the natural ones, told the same story and a second one. There are deep quakes, tied to the tides, and shallow ones, and the impacts on top of those. None of this is a sound in the air. There is no air. The ringing is a motion of the ground, written down by a machine, and it is long because the Moon has nothing to still it. The hour is the surprise. The dryness is the reason.