QUESTION:
Is there sound in space? For example, if there is an explosion in space,
could it be heard elsewhere? Is there enough gas in space to transmit sound?

ANSWER from Bob Haberle on November 7, 1997:
While there are molecules in space, they are separated by such vast
distances that they rarely hit each other. Collisions between molecules is
required for the transmission of sound waves. No collisions - no
transmission. Light waves, however, and radiation in general, can propagate
in space. That is why we can see the stars and planets. But if they make
noise, we wouldn't be able to hear it.