On Mon, 23 Feb 2004 00:33:20 GMT, "Rick Sobie"
<ricksobie@spamnotshaw.ca> wrote:

...
This occured most notably in November 1969 after seismometers were set up on the
moons surface by the astronauts of Apollo XII. When the Lunar module had taken off,
heading back to earth the astronauts discarded the ascent stage of the lunar module,
dropping it on the moons surface, smashing the craft and creating a tremor that was
picked up by the seismometers and when the NASA scientists heard the data stream,
they couldn't believe what they were hearing. The moon was ringing like a bell and
continued to do so for around an hour.

...

Maybe it was determined the moon has a hollow sphere of one kind of
material surrounding a solid core of some other.
I'd be interested in seeing data such as the frequency of the ringing,
and/or a waveform or such.   
So long as whatever the moon is composed of is elastic enough, even a
consistently solid moon would have a ring to it, kind of like a
billiard ball.  If the moon was filled with a liquid, it would have a
ring to it of some sort but would be quite different in frequency,
etc. kind of like that of a suspended drop of water, only it would be
gravity not surface tension determining the charactaristics.